The role of mitochondrial H₂S in stomatal closure induced by pathogens

PANTALENO, ROSARIO; SCUFFI, DENISE; SCHIEL. PAULA; COSTA, ALEX; CARLOS GARCIA-MATA

Mendoza

Congreso; Congreso SAIB 2022 Reunión Anual LVIII; 2022

Stomata are microscopic structures in the epidermis of most land plants, formed by a central poredelimited by pairs of highly specialized cells, the guard cells. Stomatal pores have the key physiologicalfunction of exchange gasses between the plant and its environment. Guard cells are able to senseexternal and internal stimuli and integrate them into a complex signalling network that triggers changesin the cellular volume to control pore size, leading to stomatal aperture or closure.Some bacterial and fungal pathogens use stomatal pores as a natural entrance to infect plants. As aconsequence, plants evolved to recognize conserved motifs in pathogens surface, the pathogenassociated molecular patterns (PAMPs), and trigger different signalling pathways in order to inducestomatal closure, as a first mechanical barrier to prevent infection. The gasotransmitter hydrogen sulfide(H₂S), a highly reactive molecule, participates in the modulation of different physiological processesincluding stomatal closure. Although H₂S can be produced in different subcellular compartments, the roleof mitochondrial H₂S in plants remains little explored. In this work, we present results obtained in our labshowing that mutants of the mitochondrial enzymatic source, β-cyanoalanine synthase (cas-c1) has animpairment on stomatal closure induction and a reduced apoplastic ROS production with respect to wildtype plants when treated with the bacterial PAMP flagellin (flg22). Moreover, employing geneticallyencoded sensors, we observed that guard cells from cas-c1 have altered cytosolic H2O2 levels and glutathione (GSH) oxidative status at basal conditions and in response to flg22. In summary, the resultspresented in the poster show that the mitochondrial H₂S source CAS-C1 is involved in pathogen-inducedstomatal closure.