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

作者：Marroquin Guzman Margarita; Hartline David; Wright Janet D; Elowsky Christian; Bourret Travis J; Wilson Richard A

来源：Nature Microbiology, 2017, 2(7): 17054.

DOI：10.1038/nmicrobiol.2017.54

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 defences to facilitate the growth and development of the important rice pathogen Magnaporthe oryzae in leaf cells. Nitronate monooxygenases encoded by NMO genes catalyse 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 Delta nmo2 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 Delta nmo2 mutant. Inhibiting or quenching host reactive oxygen species suppressed rice innate immune responses and allowed the Delta nmo2 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 defences that impact M. oryzae growth and BIC development.

• 出版日期2017-7