FITNESS TRANSCRIPTION FACTOR ACTS AS A NODE IN ABIOTIC AND BIOTIC STRESS RELATED PROCESSES

MENGARELLI, DIEGO ALBERTO; ZANOR MI; VALLE EM

Ciudad Autónoma de Buenos Aires

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

(1255) FITNESS TRANSCRIPTION FACTOR ACTS AS ANODE IN ABIOTIC AND BIOTIC STRESS RELATED PROCESSESDiego A. Mengarelli, Estela M. Valle, Marìa Inès ZanorInstituto de Biologìa Molecular y Celular de RosarioThe transcription factor FITNESS is highly repressed by oxidativestress. Knock-out lines (fitness) showed higher tolerance tooxidative stress generated in the chloroplast and to salt stress dueto decreased levels of ROS. When analyzed at metabolic level fitnesslines showed an increment of salicylic acid (SA). In plants,the major route of SA synthesis is the isochorismate (IC) synthasepathway. ICS1 transcripts were significantly increased in fitness mutants.SA accumulation is maintained through transcriptional regulationof EDS1 (ENHANCED DISEASE SUSCEPTIBILITY 1) andPAD4 (PHYTOALEXIN DEFICIENT 4) and also rise of endogenousSA correlates with pathogenesis-related genes induction. Transcriptionalreprogramming is controlled mainly by NPR1 (non expressorof pathogenesis-related gene 1). Monomerization and nuclear accumulationof NPR1 in the presence of SA results in PR1 increasedexpression and is therefore considered a marker for activation ofsalicylate-signalling pathway. Consistent with the increased levelsof SA measured in fitness mutants we observed an induction of bothNPR1 and PR1 transcript levels. The finding that PAD4 and EDS1transcripts are both up-regulated in fitness mutants confirms that theROS perturbation leads to modification of hormonal homeostasis.Our data indicate that altered expression of FITNESS acts modulatingSA-related processes: fitness lines show a high transcriptionalup-regulation of the SA-responsive marker gene PR1, whose expression is NPR1-dependent. Also, fitness lines resulted lesssensitive to Pseudomona syringae pv. tomato DC 3000 infection.Therefore, we postulate that FITNESS acts as a node regulatingsignal transduction pathways in response to both abiotic and bioticstresses.ROS- salicylic acid- abiotic stress-biotic stress