Role of hydrogen sulfide (H2S) and participation of calcium (Ca2+) in stomatal immunity in Arabidopsis thaliana

SCHIEL, PAULA; PANTALENO, ROSARIO; SCUFFI, DENISE; GARCÍA-MATA, CARLOS; LAXALT, ANA M.

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology; 2023

SAFV

Stomata are pores surrounded by pairs of specialized cells called guard cells (GCs). Changes in GCs turgor pressure modify the stomatal aperture, which controls gas exchange of most land plants. Some pathogens can enter into the plant through these natural apertures, so induction of the stomatal closure implies a first barrier of plant defense. This mechanism is known as stomatal immunity.The recognition of pathogens triggers an increase of cytosolic calcium (Ca2+cyt) and reactive oxygen species (ROS) in the whole plant and in GCs. Besides, the bacterial elicitor flg22, or its downstream signaling molecule Ca2+, induce stomatal closure.Hydrogen sulfide (H2S) is a gasotransmitter that has been described to induce stomatal closure. In our lab, we demonstrated that the main H2S cytosolic source L-CYSTEINE DESULFHYDRASE 1 (DES1), participates in flg22-induced stomatal closure, but a possible interaction between H2S/DES1 and Ca2+ remains to be elucidated. Additionally, stomatal closure induced by Ca2+ is impaired in des1 mutant plants. However, Ca2+cyt increase in GCs treated with flg22 shows the same dynamic as wild type plants. H2S acts mainly by persulfidation of proteins, a posttranslational modification (PTM) in cysteine residues that regulates the activity or localization of the target protein. Preliminary results obtained in our lab show several persulfidation targets associated with the immune response specifically in GCs. Among them, there is PHOSPHOLIPASE C2 (PLC2), which is involved in stomatal closure induced by flg22; and some Ca2+-dependent protein kinases. PLC2-silenced plants do not close their stomata in response to a H2S donor, and present a reduced production of cytosolic ROS in GCs when treated with it. More research needs to be done in order to know the H2S targets and the way this PTM participates in the signaling triggered by pathogens. The aim of this work is to investigate the interplay between DES1 and Ca, and the involvement of persulfidation on stomatal immunity