Inhibition of Proline Dehydrogenase and mitochondrial electron transport chain affects flg22-induced defense responses

FABRO G; ALVAREZ ME

Mar del Plata, Buenos Aires

Congreso; XV Congreso Latinoamericano, XXX Reunión Argentina, de Fisiología Vegetal; 2014

SAFV

Perception of pathogen associated molecular patterns (PAMPs) by plant cell-membrane receptors triggers rapid cellular changes (ion fluxes, oxidative burst, MAPK activation, gene-expression, callose accumulation) that together characterize PAMP-triggered immunity (PTI). Nowadays, little is known about the role of the mitochondrion and metabolisms taking place inside this organelle, like proline (Pro) catabolism, on PTI responses. We previously reported that A. thaliana plants, with reduced expression of Proline dehydrogenase (ProDH), were impaired in PTI responses to the PAMP flg22. We here characterize how ProDH inhibition by proline analogs (T4C and THFA), reduces flg22-induced ROS in a dose-dependent manner, with their effect being competed by exogenous Pro. Also, as under stress conditions ProDH activity might uncouple from P5C dehydrogenase, releasing electrons to the mitochondrial Electron Transport Chain (mETC) and generate ROS, we wondered if an altered mETC affects PTI outputs. Treatment of plants with mETC inhibitors (Antimycin and Rotenone) reduced flg22-triggered ROS and decreased resistance to P. syringae, without causing cell death. In addition, A. thaliana mutants for the mitochondrial enzyme Manganese superoxide dismutase, showed enhanced susceptibility to the bacteria Pseudomonas syringae. Therefore, our results suggest that ProDH activity and a fully functional mETC positively contribute to the establishment of PTI.