P-197 - Infection with Botrytis cinerea that lacks NADPH oxidase provides new insights into the impact of the redox environment on plant responses against this necrotroph

Abstract

Our previous studies into plants have demonstrated a correlation linking priming plant defense, callose accumulation and control of oxidative burst. We have also shown that lack of Cu–Zn superoxide dismutase BCSOD1 reduces the fungal infection associated with the interplay between O 2 - /H 2 O 2 and plant responses. Herein we studied the effect on Arabidopsis and tomato responses of the absence of the B. cinerea NADPH oxidase (Nox) complex, a major source of O 2 - production. Absence of the BcNnox complex (∆bcnoxAB) showed significantly impaired virulence to WT in both cultures. This was associated with an increase in pathogen-induced callose, an O 2 - /H 2 O 2 imbalance with increased O 2 - and reduced H 2 O 2, and the early induction of the PTI-marker WRKY53. However, ∆bcnoxAB produced different effects on the hormone-signaling pathways and redox-sensitive genes in both hosts. Our results indicated that the BcNox constitutes a virulence factor that might contribute to oxidative burst and perform additional roles with different impacts on Arabidopsis and tomato plants. The analysis of the mutants lacking catalytic subunits ∆BcNoxA and ∆BcNoxB, and the regulatory subunit ∆BcNoxR, revealed that callose always correlated with the infection phenotype in both cultures, while oxidative burst did not.