A model system for activation of complete and incomplete proline catabolism in Arabidopsis

RIZZI YS; ALVAREZ ME

Rosario

Congreso; L Reunión Anual SAIB; 2014

SAIB

Proline (Pro) metabolism affects the development of the Hypersensitive Response (HR), a local defense program against biotrophic pathogens. In particular, proline dehydrogenase (ProDH) is necessary for optimal generation of the oxidative burst, a hallmark of this response. ProDH converts Pro into Δ1 pyrroline-5-carboxylate (P5C). In the complete catabolic pathway, P5C is transformed into Glu by P5C dehydrogenase (P5CDH). In the incomplete pathway, P5C can be reconverted to Pro by P5C reductase (P5CR) activating the Pro/P5C cycle. To start dissecting the effect of ProDH on HR, we generated transgenic Arabidopsis plants allowing activation of each of these pathways. These plants carry the Est:ProDH trasgene, either in the wild type (WT) or p5cdh backgrounds. As expected, estradiol induced ProDH in WT plants. Moreover, it also activated P5CDH indicating this plant stimulated the complete catabolic pathway. On the p5cdh background, estradiol induced ProDH as in WT plants confirming stimulation of incomplete Pro catabolism. Both plants were used to analyze ROS-sensitive markers and expression of Pro biosynthetic genes. Different responses were obtained in each of them indicating that ProDH may have diverse cellular impacts depending on the possibility of coupling with the P5CDH activity.