title: Septin-Dependent Assembly of the Exocyst Is Essential for Plant Infection by Magnaporthe oryzae.
abstract: Magnaporthe oryzae is the causal agent of rice blast disease, the most devastating disease of cultivated rice (Oryza sativa) and a continuing threat to global food security. To cause disease, the fungus elaborates a specialized infection cell called an appressorium, which breaches the cuticle of the rice leaf, allowing the fungus entry to plant tissue. Here, we show that the exocyst complex localizes to the tips of growing hyphae during vegetative growth, ahead of the Spitzenkörper, and is required for polarized exocytosis. However, during infection-related development, the exocyst specifically assembles in the appressorium at the point of plant infection. The exocyst components Sec3, Sec5, Sec6, Sec8, and Sec15, and exocyst complex proteins Exo70 and Exo84 localize specifically in a ring formation at the appressorium pore. Targeted gene deletion, or conditional mutation, of genes encoding exocyst components leads to impaired plant infection. We demonstrate that organization of the exocyst complex at the appressorium pore is a septin-dependent process, which also requires regulated synthesis of reactive oxygen species by the NoxR-dependent Nox2 NADPH oxidase complex. We conclude that septin-mediated assembly of the exocyst is necessary for appressorium repolarization and host cell invasion.
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom The Sainsbury Laboratory, Norwich NR4 7UH, United Kingdom.
authors.forename: Yogesh K
authors.identifier: http://orcid.org/0000-0002-8696-9044
authors.initials: YK
authors.lastname: Gupta
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom The Sainsbury Laboratory, Norwich NR4 7UH, United Kingdom.
authors.forename: Yasin F
authors.identifier: http://orcid.org/0000-0002-9502-355X
authors.initials: YF
authors.lastname: Dagdas
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
authors.forename: Ana-Lilia
authors.identifier: http://orcid.org/0000-0002-6560-3473
authors.initials: AL
authors.lastname: Martinez-Rocha
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kershaw
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
authors.forename: George R
authors.identifier: http://orcid.org/0000-0002-8768-2598
authors.initials: GR
authors.lastname: Littlejohn
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom.
authors.forename: Lauren S
authors.identifier: http://orcid.org/0000-0003-0370-5746
authors.initials: LS
authors.lastname: Ryder
authors.affiliation: The Sainsbury Laboratory, Norwich NR4 7UH, United Kingdom.
authors.forename: Jan
authors.identifier: http://orcid.org/0000-0003-1858-2574
authors.initials: J
authors.lastname: Sklenar
authors.affiliation: The Sainsbury Laboratory, Norwich NR4 7UH, United Kingdom.
authors.forename: Frank
authors.identifier: http://orcid.org/0000-0003-2490-4824
authors.initials: F
authors.lastname: Menke
authors.affiliation: School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom n.j.talbot@exeter.ac.uk.
authors.forename: Nicholas J
authors.identifier: http://orcid.org/0000-0001-6434-7757
authors.initials: NJ
authors.lastname: Talbot
mesh_terms: D005656:Fungal Proteins / Q000378:metabolism*; D025301:Hyphae / Q000378:metabolism; D047468:Immunoprecipitation; D020082:Magnaporthe / Q000502:physiology*; D010935:Plant Diseases / Q000382:microbiology*; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport; D017382:Reactive Oxygen Species / Q000378:metabolism; D058112:Septins / Q000378:metabolism*; D013172:Spores, Fungal / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D021122:Protein Subunits; D017382:Reactive Oxygen Species; D058112:Septins