Biochemistry

Abstract

CS-21-3 - Is Elevated Carbon Dioxide-triggered Stomatal Closure Mediated via Abscisic Acid Signaling?

Tuesday, July 17
9:13 AM - 9:33 AM

Regulation of stomatal apertures in response to changing environmental conditions controls CO2 fluxes and water loss between plants and the atmosphere. Elevated [CO2] and the plant hormone abscisic acid (ABA) trigger stomatal closure, but remains a matter or debate whether elevated [CO2]-triggered stomatal closure is mediated via a rapid rise in ABA concentration and it remains unknown where these pathways converge. To address these questions, stomatal CO2 responses were analyzed in ABA synthesis mutants and in ABA receptor mutants. Time-resolved gas exchange analyses show that ABA synthesis mutants and ABA receptor mutants respond to [CO2] elevation, whereas the response kinetics are altered. However, these analyses do not distinguished whether CO2 elevates ABA in guard cells or whether CO2 and ABA transduction converge further downstream at a defined point. We have pursued additional experiments in several mutant backgrounds and report patch-clamp analyses of guard cell anion channel regulation and guard cell biochemical analyses of ABA ad CO2 signaling. Further, we have use newly developed real-time ABA FRET nano-reporter plants to determine whether CO2 concentration changes cause rapid ABA concentration changes in guard cells. Taken together these interdisciplinary investigation point to a new and unexpected understanding of how CO2 signaling and ABA signaling both close stomata.


 

Co-Authors

Po-Kai Hsu – Division of Biological Sciences, University of California, San Diego, USA; Shintaro Munemasa – Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan; Yohei Takahashi – Division of Biological Sciences, University of California, San Diego, USA; Ebe Merilo – Institute of Technology, University of Tartu, Tartu, Estonia; Jingbo Zhang – Division of Biological Sciences, University of California, San Diego, USA; Rainer Waadt – Centre for Organismal Studies, Plant Developmental Biology, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany; Hannes Kollist – Institute of Technology, University of Tartu, Tartu, Estonia

Julian Schroeder, PhD

Prof.
Division of Biological Sciences, UC San Diego

Julian Schroeder pioneered the identification and characterization of plasma membrane ion channels in higher plants. He characterized and identified their functions and regulation mechanisms, in particular in stomatal guard cell signal transduction and abiotic stress resistance. He has identified mechanisms of abscisic acid signal transduction. He has further characterized mechanisms through which plants are responding to the continuing elevation in atmospheric CO2 in closing stomatal pores. His laboratory also identified and characterized the plant HKT transporters and identified how HKT transporters protect plants from salinity/sodium stress. He is member of the U.S. National Academy of Sciences, the German National Academy of Sciences Leopoldina and Fellow of the American Association for the Advancement of Science. He has received awards, including the NSF Presidential Young Investigator Award and was a CAS International Visiting Professor and is Churchill Overseas Fellow at Cambridge University.

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