An optimized genetically encoded dual reporter for simultaneous ratio imaging of Ca2+ and H+ reveals new insights into ion signaling in plants

Author(s)

Li, Kunkun ^[1] ; Prada, Juan ^[2] ; Damineli, Daniel S. C. ^{[3, 4]} ; Liese, Anja ^[5] ; Romeis, Tina ^[5] ; Dandekar, Thomas ^[2] ; Feijo, Jose A. ^[3] ; Hedrich, Rainer ^[1] ; Konrad, Kai Robert ^[1]

Affiliation

^[1] Univ Wurzburg, Julius Von Sachs Inst Biosci, Dept Bot 1, D-97082 Wurzburg - Germany

^[2] Univ Wurzburg, Dept Bioinformat, D-97074 Wurzburg - Germany

^[3] Univ Maryland, Dept Cell Biol & Mol Genet, 2136 Biosci Res Bldg, College Pk, MD 20742 - USA

^[4] Univ Sao Paulo, Fac Med, Dept Pediat, BR-01246903 Sao Paulo, SP - Brazil

^[5] Leibniz Inst Plant Biochem, D-06120 Halle, Saale - Germany

• Document type: Journal article
• Source: NEW PHYTOLOGIST; v. 230, n. 6 FEB 2021.
• Web of Science Citations: 1

Abstract

Whereas the role of calcium ions (Ca2+) in plant signaling is well studied, the physiological significance of pH-changes remains largely undefined. Here we developed CapHensor, an optimized dual-reporter for simultaneous Ca2+ and pH ratio-imaging and studied signaling events in pollen tubes (PTs), guard cells (GCs), and mesophyll cells (MCs). Monitoring spatio-temporal relationships between membrane voltage, Ca2+- and pH-dynamics revealed interconnections previously not described. In tobacco PTs, we demonstrated Ca2+-dynamics lag behind pH-dynamics during oscillatory growth, and pH correlates more with growth than Ca2+. In GCs, we demonstrated abscisic acid (ABA) to initiate stomatal closure via rapid cytosolic alkalization followed by Ca2+ elevation. Preventing the alkalization blocked GC ABA-responses and even opened stomata in the presence of ABA, disclosing an important pH-dependent GC signaling node. In MCs, a flg22-induced membrane depolarization preceded Ca2+-increases and cytosolic acidification by c. 2 min, suggesting a Ca2+/pH-independent early pathogen signaling step. Imaging Ca2+ and pH resolved similar cytosol and nuclear signals and demonstrated flg22, but not ABA and hydrogen peroxide to initiate rapid membrane voltage-, Ca2+- and pH-responses. We propose close interrelation in Ca2+- and pH-signaling that is cell type- and stimulus-specific and the pH having crucial roles in regulating PT growth and stomata movement. (AU)

• FAPESP's process: 19/23343-7 - Temporal analysis of gene expression
• Grantee: Daniel Santa Cruz Damineli
• Support Opportunities: Scholarships in Brazil - Post-Doctoral