Cyclic mononucleotides modulate potassium and calcium flux responses to H 2 O 2 in Arabidopsis roots

Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H 2 O 2 ) induces rapid net K + ‐efflux and Ca 2+ ‐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 Ca 2+ ‐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 H 2 O 2 .