High robustness of cytosolic glutathione redox potential under combined salt and osmotic stress in barley as revealed by the biosensor Grx1-roGFP2

O_LIBarley is a staple crop of major global importance and relatively resilient to a wide range of stress factors in the field. Transgenic reporter lines to investigate physiological parameters during stress treatments remain scarce. C_LIO_LIWe generated and characterized stable homozygous barley lines (cv. Golden Promise Fast) expressing the genetically-encoded biosensor Grx1-roGFP2, which indicates the redox potential of the major antioxidant glutathione in the cytosol. C_LIO_LIOur results demonstrate functionality of the sensor in living barley plants. We determined the glutathione redox potential (EGSH) of the cytosol to be in the range of -308 to -320 mV. EGSH was robust against a combined NaCl (150 mM) and water deficit treatment (-0.8 MPa) that caused growth retardation and showed only a minor oxidation after 96 h of treatment. C_LIO_LIWe conclude that the generated reporter lines are a novel resource to study stress resilience in barley. C_LI One sentence summaryGeneration and characterization of barley plants stably expressing Grx1-roGFP2 reveal high robustness of cytosolic glutathione redox potential (EGSH) under combined salt and osmotic stress.