The role of mitochondrial H2S in stomatal immunity

PANTALENO, ROSARIO; SCUFFI, DENISE; COSTA, ALEX; GARCÍA-MATA, CARLOS

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology; 2023

SAFV

Land plants have little holes in their epidermis, known as stomata, responsible for the gas exchange between plants and their environment. Stomata are formed by pairs of specialized cells, the guard cells, delimitating a central pore. Guard cells sense different stimuli and integrate them into a complex signalling network that regulates the pore size. When compared with their neighboring cells, guard cells have unique characteristics, like a higher mitochondrial density and respiration rate. Nevertheless, the role of mitochondrial activity on stomatal closure is not fully understood.Some pathogens use natural apertures like stomatal pores to invade plants. Hence, plants evolved to recognize conserved motifs in pathogens, the pathogen-associated molecular patterns (PAMPs). The perception of PAMPs triggers multiple defense responses, including ROS production, gene reprogramming and stomatal closure, as a first mechanical barrier to reduce infection.The gasotransmitter hydrogen sulfide (H₂S), is a very reactive molecule that regulates different physiological processes, including stomatal closure. Despite that Arabidopsis has enzymatic H2S sources in different subcellular compartments, most works on the biological effect of H2S in plants have focused on the main cytosolic source DES1. In this work, we studied the role of the mitochondrial H2S source β-CYANOALANINE SYNTAHASE (CAS-C1) on stomatal immunity. Previous results obtained in our lab show that flg22-triggered stomatal closure, apoplastic and cytosolic ROS increase, were impaired in cas-c1. In this work, we present evidence indicating that cas-c1 shows a differential expression of flg22-induced genes . Moreover, using radiometric sensors we show that flg22 increases the mitochondrial activity in guard cells, response that is disrupted in cas-c1. Taken together, results suggest that CAS-C1 is needed for flg22-induced stomatal immunity, response that involves mitochondrial activity.