Identification and characterization of suppressors of plant cell death (SPD) effectors from Magnaporthe oryzae.
Phytopathogenic microorganisms, including the fungal pathogen Magnaporthe oryzae, secrete a myriad of effector proteins to facilitate infection. Utilizing the transient expression of candidate effectors in the leaves of the model plant Nicotiana benthamiana, we identified 11 suppressors of plant cell death (SPD) effectors from M. oryzae that were able to block the host cell death reaction induced by Nep1. Ten of these 11 were also able to suppress BAX-mediated plant cell death. Five of the 11 SPD genes have been identified previously as either essential for the pathogenicity of M. oryzae, secreted into the plant during disease development, or as suppressors or homologues of other characterized suppressors. In addition, of the remaining six, we showed that SPD8 (previously identified as BAS162) was localized to the rice cytoplasm in invaded and surrounding uninvaded cells during biotrophic invasion. Sequence analysis of the 11 SPD genes across 43 re-sequenced M. oryzae genomes revealed that SPD2, SPD4 and SPD7 have nucleotide polymorphisms amongst the isolates. SPD4 exhibited the highest level of nucleotide diversity of any currently known effector from M. oryzae in addition to the presence/absence polymorphisms, suggesting that this gene is potentially undergoing selection to avoid recognition by the host. Taken together, we have identified a series of effectors, some of which were previously unknown or whose function was unknown, that probably act at different stages of the infection process and contribute to the virulence of M. oryzae.
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
William
W
Sharpee
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
Yeonyee
Y
Oh
Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA.
Mihwa
M
Yi
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
William
W
Franck
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
Alex
A
Eyre
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
Laura H
LH
Okagaki
Department of Plant Pathology, Kansas State University, Manhattan, KS, 66506, USA.
Barbara
B
Valent
Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, 27606, USA.
Ralph A
RA
Dean
D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D020082:Magnaporthe / Q000378:metabolism* / Q000472:pathogenicity*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology*; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology; D014026:Nicotiana / Q000378:metabolism* / Q000382:microbiology*
D005656:Fungal Proteins
effector; rice blast; suppressor