OXIDATIVE STRESS RESPONSIVE TRANSCRIPTION FACTOR FITNESS REGULATES ARABIDOPSIS RESPONSES TO PSEUDOMONAS INFECTION

MENGARELLI DA; ZANOR MI; ROLDAN TEWES L; VALLE EM

Montpellier

Congreso; IPMB2018; 2018

International Society of Plant Molecular Biology

The transcription factor FITNESS is highly repressed by oxidative stress and FITNESS expression is positively correlated with ROS accumulation. Plants lacking FITNESS expression (fitness lines) showed higher tolerance to oxidative stress generated in the chloroplast and an accumulation of salicylic acid (SA). Taking this into account, we examined plant disease signalling and susceptibility in FITNESS lines. We observed an induction of both NPR1 and PR1 transcript levels and additionally PAD4 and EDS1 transcripts were up-regulated in fitness lines confirming that ROS perturbation leads to modification of hormonal homeostasis. Lack of FITNESS expression resulted in plants less sensitive to the hemi-biotrophic pathogen Pseudomona syringae pv. tomato DC 3000 infection. On the contrary, FITNESSox lines were more susceptible to this infection. By analysing the double mutant fitness npr1- 1 we explored further the relationship between FITNESS and SA signalling pathways. After pathogen infection, double mutant plants showed a supressed resistant phenotype indicating that fitness acts at least partially through activation of NPR1. In summary, we postulate that FITNESS regulates signal transduction pathways promoting a priming in plant defense.