A longstanding question in plant physiology concerns the mechanisms of Na+ influx into the plant root (1). Recently we characterised membrane transporters (3) that form a putative pathway for Na+ uptake in Arabidopsis (2). At the molecular level, so called voltage independent ion channels (VICs) can be recorded using the patch clamp technique . These channels are Na+ permeable. Interestingly, there are VICs present in root plasma membranes that are inactivated by cyclic nucleotides, providing for the first time evidence for a regulatory mechanism of this class of channel. A direct involvement of these ion channels in Na+ uptake is shown by a cyclic nucleotide dependent inhibition of the unidirectional Na+ influx in intact roots. Thus, VIC inactivation by cyclic nucleotides reduces Na+ influx which translates itself to reduced Na+ accumulation at the whole plant level and improved plant salt tolerance. The latter can be shown directly by growing seedlings in the presence of membrane permeable cyclic nucleotides. The work suggests the presence in plants of a cyclic nucleotide-based signalling pathway that functions through modulating ion channel activity.