Contributions of Proline Dehydrogenase to cellular redox alterations associated to plant immunity

YANINA SOLEDAD RIZZI; GEORGINA FABRO; MARIA ELENA ALVAREZ

Fos de Iguazú

Congreso; 11th International Congress of Plant Molecular Biology IPMB 2015; 2015

Brazilian Genetics Society and MINCyT Argentina

Proline (Pro) is converted into glutamic acid by the subsequent action of Pro dehydrogenase (ProDH) and Delta 1-pyrroline-5-carboxilate (P5C) dehydrogenase (P5CDH), having P5C as intermediate. Arabidopsis contains two genes encoding ProDH (ProDH1 and ProDH2), whose silencing reduces HR development and ROS levels. The current work evaluates the contribution of each of these genes to defenses against different kinds of pathogens. In addition, we analyze the mechanisms underlying the ProDH effects on HR. At basal and post-infection conditions abnormal expression of ProDH1 occurs in the prodh2 mutant, and viceversa. prodh1 and prodh2 plants are hyper susceptible to Pseudomonas syringae pv. tomato and Botrytis cinerea, suggesting the enzyme has a wide effect on plant immunity. During the onset of HR, ProDH and P5CDH become uncoupled, with the first enzyme apparently participating in the Pro/P5C cycle that is suspected to generate ROS. To test this possibility, we constructed Est:ProDH transgenic plants in the wild type and p5cdh backgrounds and evaluated the expression of intracelular redox markers after transgene activation. Our results indicate that several cellular compartments alter their redox status after ProDH activation. In addition, we observed that ProDH potentiates the activity of the NADPH oxidase.