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NADPH oxidase regulates chemotropic growth of the fungal pathogen Fusarium oxysporum towards the host plant
Author(s) -
Nordzieke Daniela Elisabeth,
Fernandes Tânia R.,
El Ghalid Mennat,
Turrà David,
Di Pietro Antonio
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16085
Subject(s) - fusarium oxysporum , nadph oxidase , biology , superoxide dismutase , reactive oxygen species , microbiology and biotechnology , protein kinase a , biochemistry , kinase , botany , enzyme
Summary Soil‐inhabiting fungal pathogens use chemical signals to locate and colonise the host plant. In the vascular wilt fungus Fusarium oxysporum , hyphal chemotropism towards tomato roots is triggered by secreted plant peroxidases (Prx), which catalyse the reductive cleavage of reactive oxygen species (ROS). Here we show that this chemotropic response requires the regulated synthesis of ROS by the conserved fungal NADPH oxidase B (NoxB) complex, and their transformation into hydrogen peroxide (H 2 O 2 ) by superoxide dismutase (SOD). Deletion of NoxB or the regulatory subunit NoxR, or pharmacological inhibition of SOD, specifically abolished chemotropism of F. oxysporum towards Prx gradients. Addition of isotropic concentrations of H 2 O 2 rescued chemotropic growth in the noxB Δ and noxR Δ mutants, but not in a mutant lacking the G protein‐coupled receptor Ste2. Prx‐triggered rapid Nox‐ and Ste2‐dependent phosphorylation of the cell wall integrity mitogen‐activated protein kinase (CWI MAPK) Mpk1, an essential component of the chemotropic response. These results suggest that Ste2 and the CWI MAPK cascade function downstream of NoxB in Prx chemosensing. Our findings reveal a new role for Nox enzymes in directed hyphal growth of a filamentous pathogen towards its host and might be of broad interest for chemotropic interactions between plants and root‐colonising fungi.