Polyamines prevent NaCl-induced K+ efflux from pea mesophyll by blocking non-selective cation channels

Despite numerous reports implicating polyamines in plant salinity responses, the specific ionic mechanisms of polyamine-mediated adaptation to salt-stress remain elusive. In this work, we show that micromolar concentrations of polyamines are efficient in preventing NaCl-induced K+ efflux from the leaf mesophyll, and that this effect can be attributed to the inhibition of non-selective cation channels in mesophyll. The inhibition by externally applied polyamines developed slowly over time, suggesting a cytosofic mode of action. Overall, we suggest that elevated levels of cellular polyamine may modulate the activity of plasma membrane ion channels, improving ionic relations and assisting in a plant's adaptation to salinity. (C) 2007 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.