A recombinant plant natriuretic peptide causes rapid and spatially differentiated K⁺, Na⁺ and H⁺ flux changes in Arabidopsis thaliana roots

Plant natriuretic peptides (PNPs) belong to a novel class of systemically mobile molecules that are structurally similar to the N-terminal domain of expansins and affect physiological processes such as protoplast volume regulation at nano-molar concentrations. Here we demonstrate that AtPNP-A, a recombinant Arabidopsis thaliana PNP causes rapid H+ influx in the elongation zone of A. thaliana roots but not in the mature zone. AtPNP-A also induces significant K+ and Na+ efflux and this effect is seen in the mature root zone only. These observations suggest that responses to AtPNP-A are developmental stage and tissue specific and point to a complex role in plant growth and homeostasis.