Transcriptional regulation of proline-catabolism genes under stress conditions

MONTEOLIVA MI; CECCHINI NM; ÁLVAREZ ME

Va Carlos Paz, Córdoba

Congreso; XLIV Reunión de la Sociedad Argentina de Bioquímica y Biología Molecular; 2008

Sociedad Argentina de Bioquímica y Biología Molecular

Proline (Pro) catabolism involves the consecutive activity of Pro dehydrogenase (ProDH) and P5C dehydrogenase (P5CDH), which generate delta 1-pyrroline-5-carboxilate (P5C) and glutamate, respectively. Both enzymes have mitochondrial localization. ProDH gene expression is induced by exogenous Pro and salicylic acid (SA), as well as by the attack of avirulent pathogen. Some of these conditions also alter P5CDH gene expression. In addition, P5CDH transcript levels are regulated by SRO5-P5CDH natural siRNA, induced by oxidative stress and salinity. Uncoupled ProDH and P5CDH activities may generate accumulation of P5C, a proposed inducer of apoptosis in animals. P5C is a highly unstable metabolite which quantification in plant tissues has severe limitations. We evaluated if in tissues triggering hypersensitive cell death, ProDH, P5CDH and SRO5 transcript levels are compatible with P5C accumulation. Also we analyze transcriptional cross-regulation between ProDH and P5CDH by evaluating stress-induced gene expression changes in ProDH knockdown plants and in p5cdh T-DNA mutant lines.