Generation of reactive oxygen species by fungal NADPH oxidases is required for rice blast disease.
One of the first responses of plants to microbial attack is the production of extracellular superoxide surrounding infection sites. Here, we report that Magnaporthe grisea, the causal agent of rice blast disease, undergoes an oxidative burst of its own during plant infection, which is associated with its development of specialized infection structures called appressoria. Scavenging of these oxygen radicals significantly delayed the development of appressoria and altered their morphology. We targeted two superoxide-generating NADPH oxidase-encoding genes, Nox1 and Nox2, and demonstrated genetically, that each is independently required for pathogenicity of M. grisea. Deltanox1 and Deltanox2 mutants are incapable of causing plant disease because of an inability to bring about appressorium-mediated cuticle penetration. The initiation of rice blast disease therefore requires production of superoxide by the invading pathogen.
Egan
Martin J
MJ
School of Biosciences, Washington Singer Laboratories, University of Exeter, Perry Road, Exeter EX4 4QG, United Kingdom.
Wang
Zheng-Yi
ZY
Jones
Mark A
MA
Smirnoff
Nicholas
N
Talbot
Nicholas J
NJ
D020082:Magnaporthe / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D012275:Oryza / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
D017382:Reactive Oxygen Species; D013481:Superoxides; D019255:NADPH Oxidases