cGMP modulates gene transcription and cation transport in Arabidopsis roots

The occurrence of the second messenger 3',5'-cyclic guanyl monophosphate (cGMP) has been shown in a number of plant species, including barley, tobacco and Arabidopsis. Physiological processes where cGMP signalling has been observed, or has been inferred, to play a role include chloroplast development, alpha-amylase production in aleurone tissue, NO-dependent expression of defence-related genes and salt/osmotic stress. In most cases, it is unknown how cGMP exerts its effects and what the downstream targets are. A transcriptomics approach was therefore used to identify putative targets for cGMP signalling. Root exposure to 10 mu M membrane permeable cGMP induced changes in abundance for many transcripts involved in metabolism, gene transcription, signalling and defence. In particular, monovalent cation transporters such as non-selective ion channels and cation:proton antiporters were found to be affected in cGMP exposed roots. In addition, exposure to cGMP was found to modulate influx and efflux of the monovalent cations Na+ and K+.