The Role Of Heterotrimeric G Protein In EATP-regulated Plasma Membrane Ion Channel Activity In Arabidopsis Thaliana

eATP played an important role in plant development and environment adaptation. It has been reported that eATP promoted Ca2+ influx through hyperpolarization-activated calcium channel in plasma membrane of root epidermal cells, resulting in cytosolic calcium concentration elevation.In order to investigate whether heterotrimeric G protein was involved in eATP regulated PM ion channel activation, heterotrimeric G protein alpha subunit mutants of Arabidopsis thaliana were used as material, the effect of added ATP on Ca2+ channel and K+ channel activity in PM of root epidermal cell protoplasts was investigated by using patch clamp.By using whole-cell voltage-clamping, hyperpolarization-activated Ca2+ channels in plasma membrane of Arabidopsis root cell was detected. Exogenous ATP promoted Ca2+ channel activity, the opening voltage elevated and maximum current increased after ATP stimulation in wild type. In null mutants of heterotrimeric G proteinαsubunit, eATP stimulated Ca2+ channel activation was remarkably suppressed. In over-expression lines, eATP stimulated calcium channel activation stronger than that in wild type. These data suggest that heterotrimeric G protein played an important role in eATP regulated calcium channel activation.In order to investigate whether heterotrimeric G protein was involved in eATP regulated PM potassium channel activation. By using whole-cell voltage-clamping, both inward and outward potassium channels in plasma membrane of Arabidopsis root cell was detected. Exogenous ATP promoted outward potassium channel activity, the opening voltage elevated and maximum current increased after ATP stimulation in wild type, but the inward potassium current and voltage have no change campared with before it was treated. In null mutants of heterotrimeric G proteinαsubunit, eATP stimulated both inward and outward potassium channels activation was remarkably suppressed. In over-expression lines, eATP stimulated outward potassium channel activation stronger than that in wild type, the inward potassium current and voltage also have no change campared with before it was treated. These data suggest that heterotrimeric G protein played an important role in eATP regulated outward potassium channel activation, but for the activity of inward potassium channel had little effect.Summing up the above results and our previous results, we suggest that heterotrimeric G protein played an important role in eATP promoted inward calcium channels and outward potassium channel activation in Arabidopsis root epidermal cells.