Decoding the interaction between Nitric Oxide and hydrogen sulfide in stomatal movement

Abstract

Stomatal pore regulation is a key process for carbon and water homeostasis of terrestrial plants. The pore size is modulated through changes in the guard cell volume, driven by variations in the osmotic potential of the guard cells. This process is closely regulated by a complex signaling network that involves the participation of several second messengers including gasotransmitters. The importance of gaseous molecules in signaling has been highlighted in the last decade and, in plants, has been reported to modulate many adaptive responses todifferent biotic and abiotic stresses including the regulation of stomatal movement in response to drought stress. Nitric oxide (NO) and hydrogen sulfide (H2S) have been reported to close the stomata in different plant species, and itsthe production, mode of action, and interplay between them and with other molecules are under constant review. Recently, the interest in animal research has drifted to the functional role of nitroxyl (HNO/NO−), an alternative redox form of NO which is formed by biochemical reactions between H2S and NO in vivo. It has been reported that HNO has effects in different processes, and several works have studied the interaction between H2S and different NO donors demonstrating the formation of new chemical species.One of them is the formation of HNO from the mixture of NaHS, a H S donor, and SNP, a NO donor. In our lab, we have preliminary data showing that HNO blocks H2S dependent stomatal closure in Vicia faba.Interestingly, no stomatal closure induction was evidenced when SNP and NaHS were added together, supporting the interaction between these two gasotransmitters.In the current chapter, we summarize the current knowledge and updates on the role of NO and H2S in guard cell signaling.