A novel hydrogen sulfide donor causes stomatal opening and reduces nitric oxide accumulation

Effects of hydrogen sulfide (H2S) on plant physiology have been previously studied, but such studies have relied on the use of NaSH as a method for supplying H2S to tissues. Now new compounds which give a less severe H2S shock and a more prolonged exposure to H2S have been developed. Here the effects of one such compound, GYY4137, has been investigated to determine its effects on stomatal closure in Arabidopsis thaliana. It was found that both NaSH and GYY4137 caused stomatal opening in the light and prevented stomatal closure in the dark. Nitric oxide (NO) has been well established as a mediator of stomatal movements and here it was found that both NaSH and GYY4137 reduced the accumulation of NO in guard cells, perhaps suggesting a mode of action for H2S in this system. GYY4137, and future related compounds, will be important tools to unravel the effects of plant exposure to H2S and to determine how H2S may fit into plant cell signalling pathways.