The Magnaporthe oryzae nitrooxidative stress response suppresses rice innate immunity during blast disease

Authors

Margarita Marroquin-Guzman, University of Nebraska-LincolnFollow
David E. Hartline, University of Nebraska-LincolnFollow
Janet D. Wright, University of Nebraska-LincolnFollow
Christian G. Elowsky, University of Nebraska-LincolnFollow
Travis J. Bourret, Creighton University
Richard A. Wilson, University of Nebraska-LincolnFollow

ORCID IDs

Christian G. Elowsky

Document Type

Article

Date of this Version

2017

Citation

Published in Nature Microbiology 2 (2017), 17054. doi 10.1038/nmicrobiol.2017.54.

Comments

Copyright © 2017 Macmillan Publishers Limited. Used by permission.

Abstract

Understanding how microorganisms manipulate plant innate immunity and colonize host cells is a major goal of plant pathology. Here, we report that the fungal nitrooxidative stress response suppresses host defenses to facilitate the growth and development of the important rice pathogen Magnaporthe oryzae in leaf cells. Nitronate monooxygenases encoded by NMO genes catalyze the oxidative denitrification of nitroalkanes. We show that the M. oryzae NMO2 gene is required for mitigating damaging lipid nitration under nitrooxidative stress conditions and, consequently, for using nitrate and nitrite as nitrogen sources. On plants, the Δnmo2 mutant strain penetrated host cuticles like wild type, but invasive hyphal growth in rice cells was restricted and elicited plant immune responses that included the formation of cellular deposits and a host reactive oxygen species burst. Development of the M. oryzae effector-secreting biotrophic interfacial complex (BIC) was misregulated in the Δnmo2 mutant. Inhibiting or quenching host reactive oxygen species suppressed rice innate immune responses and allowed the Δnmo2 mutant to grow and develop normally in infected cells. NMO2 is thus essential for mitigating nitrooxidative cellular damage and, in rice cells, maintaining redox balance to avoid triggering plant defenses that impact M. oryzae growth and BIC development.