Abstract
In animals, NO-mediated production of cGMP is a crucial signaling pathway that controls numerous different cellular functions. In plants, conflicting results are obtained. This signaling mechanism remains a mystery.
Sawa et al. (2007) reported that a novel NO derivative of cGMP, 8-NO2-cGMP (NcGMP), acts as a second messenger in animals. We intend to study the role of this compound in plant cell signaling. Stomatal closure is induced by NcGMP, but not by 8-BrcGMP, whereas stomatal opening in the dark is induced by 8-Br-cGMP but not NcGMP, indicating that cGMP and its nitrated derivative act as signaling molecules in different signaling pathways. Furthermore, inhibitors of cADP-ribose synthesis and EGTA reversed NcGMP-induced stomatal closure, indicating that NcGMP is upstream of cADPR and Ca. The inhibitor of phospholipase D reversed NO-induced stomatal closure but not NcGMP-induced stomatal closure; this pathway is NO signaling from NcGMP.
