Effect of lost of proline degradation in plant-pathogen interactions

CECCHINI N; ALVAREZ ME

Carlos Paz, Córdoba

Congreso; XLIV Reunión SAIB; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

EFFECT OF THE LOST OF PROLINE DEGRADATION IN PLANT-PATHOGEN INTERACTIONS

Cecchini, Nicolás M. and Alvarez, María E.

CIQUIBIC-CONICET, Dpto. Química Biológica, Facultad Ciencias Químicas, UNC, 5000-Córdoba, Argentina.

E-mail: nicolas@dqb.fcq.unc.edu.ar

Although L-proline (Pro) accumulated in plants is correlated with stress tolerance during many situations, external Pro treatments is toxic and induce cell death through ROS production. We have recently found that tissues triggering the Hypersensitive Response (HR) upon recognition of avirulent pathogen activate Pro degradation. In early infection times, genes controlling Pro degradation (ProDH, P5CDH) displayed specific alterations in the tissues that will trigger death (these changes involve induction of ProDH, without activation of P5CDH) but not in the periferical. Similar uncoupled regulation of these genes was obtained in response to treatment with the defense hormone salicylic acid (SA). Consistently, here we show that mutants in SA pathway, sid2 and npr1, display a retarded Pro metabolism transcriptional response. Taking account the possible importance of Pro degradation in HR, we constructed siRNAProDH lines to analyze the effects of lost of the first Pro catabolic enzyme. Silenced plants showed diminution of pollen viability, different response to Pro treatment and alterations in chloroplast morphology. Moreover, these lines showed different pattern and diminished cell death during avirulent infections. These results point out an important role for Pro degradation in biotic defence responses.