Cyclic mononucleotides modulate potassium and calcium flux responses to H2O2 in Arabidopsis roots

Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H₂O₂) induces rapid net K⁺-efflux and Ca²⁺-influx in Arabidopsis roots. Pre-treatment with either 10 μM cAMP or cGMP for 1 or 24 h does significantly reduce net K⁺-leakage and Ca²⁺-influx, and in the case of the K⁺-fluxes, the cell permeant cyclic mononucleotides are more effective. We also examined the effect of 10 μM of the cell permeant 8-Br-cGMP on the Arabidopsis microsomal proteome and noted a specific increase in proteins with a role in stress responses and ion transport, suggesting that cGMP is sufficient to directly and/or indirectly induce complex adaptive changes to cellular stresses induced by H₂O₂.