The gasotransmitter Hydrogen sulfide (H2S) acts upstream of H2O2 and phospholipase D (PLD)-derived phosphatidic acid (PA) during stomatal closure.

SCUFFI, D., LAXALT, AM., LAMATTINA, L., GARCÍA-MATA, C.

Congreso; INTERNATIONAL CONGRESS OF PLANT MOLECULAR BIOLOGY; 2015

Stomatal pore regulation is a key process for carbon and water homeostasis of terrestrial plants. Abscisic acid (ABA), the most studied regulator of stomatal movement, induces stomatal closure through volume changes in guard cells. Among the second messengers that participate in ABA-induced stomatal closure are hydrogen sulfide (H2S), H2O2 and phospholipase D (PLD)-derived phosphatidic acid (PA).H2S is a small gas considered as the third endogenous gasotransmitter in both animals and plants. In Arabidopsis thaliana, H2S is enzymatically produced in the cytosol by the L-cysteine desulfhydrase 1 (DES1) and is required ABA-induced stomatal closure. In our lab we have shown that H2S induces stomatal closure in epidermal peels from different plant species. Moreover we have demonstrated in Arabidopsis that both PLDα1 and PLDδ isoforms are required for ABA-induced stomatal closure. In this work we demonstrate the existence of an interaction between H2S, H2O2 and PLD-derived PA during stomatal closure. Results show that DES1 mutants des1-1 and des1-2 close the stomata normally in response to H2O2. However, exogenous addition of 100 µM NaHS, a H2S donor, do not induces stomatal closure when epidermal peels from Arabidopsis wild type plants are treated with DPI, an inhibitor of NADPH oxidase activity. H2S-induced stomatal closure is also impaired in epidermal peels of pldα1 and pldδ single mutants. Furthermore, exogenous H2S induces an increase of 40% of PA in leaf disc of Arabidopsis wild type but not in pldα1 and pldδ single mutant plants. All together, the presented data strongly support that H2S is acting upstream of H2O2 and PA during stomatal closure in Arabidopsis thaliana.