Minimal influence of G-protein null mutations on ozone-induced changes in gene expression, foliar injury, gas exchange and peroxidase activity in Arabidopsis thaliana L

Ozone (O3) uptake by plants induces signaling processes involving the membrane-bound heterotrimeric G-protein complex. To investigate the role of this complex in the development of O3 injury, we evaluated G-protein participation in genetic, biochemical and physiological responses of Arabidopsis to O3. Transcript levels of GPA1, AGB1 and RGS1 transiently increased in Col-0 exposed to 125 ppb O3 compared with the control. However, silencing of and β G-protein genes resulted in little alteration of many processes associated with O3 injury, including the induction of ROS-signaling genes, increased leaf tissue ion leakage, decreased net photosynthesis and stomatal conductance, and increased peroxidase activity. These results indicated that many responses to O3 stress at physiological levels were not detectably influenced by and β G-proteins.