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Global genome and transcriptome analyses of Magnaporthe oryzae epidemic isolate 98-06 uncover novel effectors and pathogenicity-related genes, revealing gene gain and lose dynamics in genome evolution.

Dong Y, Li Y, Zhao M, Jing M, Liu X, Liu M, Guo X, Zhang X, Chen Y, Liu Y, Liu Y, Ye W, Zhang H, Wang Y, Zheng X, Wang P, Zhang Z - PLoS Pathog. (2015)

Bottom Line: A unique 1.4 Mb of genomic sequences was found in isolate 98-06 in comparison to reference strain 70-15.In addition, 134 candidate effectors with various segregation patterns were identified.Characterization of isolate-specific effector candidates Iug6 and Iug9 and PaR candidate Iug18 revealed that they have a role in fungal propagation and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China; Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China.

ABSTRACT
Genome dynamics of pathogenic organisms are driven by pathogen and host co-evolution, in which pathogen genomes are shaped to overcome stresses imposed by hosts with various genetic backgrounds through generation of a variety of isolates. This same principle applies to the rice blast pathogen Magnaporthe oryzae and the rice host; however, genetic variations among different isolates of M. oryzae remain largely unknown, particularly at genome and transcriptome levels. Here, we applied genomic and transcriptomic analytical tools to investigate M. oryzae isolate 98-06 that is the most aggressive in infection of susceptible rice cultivars. A unique 1.4 Mb of genomic sequences was found in isolate 98-06 in comparison to reference strain 70-15. Genome-wide expression profiling revealed the presence of two critical expression patterns of M. oryzae based on 64 known pathogenicity-related (PaR) genes. In addition, 134 candidate effectors with various segregation patterns were identified. Five tested proteins could suppress BAX-mediated programmed cell death in Nicotiana benthamiana leaves. Characterization of isolate-specific effector candidates Iug6 and Iug9 and PaR candidate Iug18 revealed that they have a role in fungal propagation and pathogenicity. Moreover, Iug6 and Iug9 are located exclusively in the biotrophic interfacial complex (BIC) and their overexpression leads to suppression of defense-related gene expression in rice, suggesting that they might participate in biotrophy by inhibiting the SA and ET pathways within the host. Thus, our studies identify novel effector and PaR proteins involved in pathogenicity of the highly aggressive M. oryzae field isolate 98-06, and reveal molecular and genomic dynamics in the evolution of M. oryzae and rice host interactions.

No MeSH data available.


Related in: MedlinePlus

Iug6, Iug9, Nup1, Nup2, and Nup3 suppress the cell death triggered by BAX.(A) Agroinfiltration sites in N. benthamiana leaves expressing Iug6, Iug9, Nup1, Nup2, or Nup3 were challenged with A. tumefaciens expressing the BAX elicitin. The BAX-induced cell death was scored at 3 and 4 DAI. A. tumefaciens strain carrying pGR106-GFP was used as a negative control, and pGR106-BAX as a positive control. (B) Western blot analysis of GFP, Iug6, Iug9, Nup1, Nup2, Nup3, and Bax protein levels in plant tissues treated above. Proteins were extracted 60 h after the last infiltration. Equal amounts of protein lysate were loaded in each lane, as verified by Ponceau S staining. (C) Presence or absence polymorphisms of each candidate effectors are indicated by a colored or black tile across the 29 field isolates. Colored tile, presence; black tile, absence. Presence /absence patterns (top) and isolates (left) were hierarchically clustered.
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ppat.1004801.g005: Iug6, Iug9, Nup1, Nup2, and Nup3 suppress the cell death triggered by BAX.(A) Agroinfiltration sites in N. benthamiana leaves expressing Iug6, Iug9, Nup1, Nup2, or Nup3 were challenged with A. tumefaciens expressing the BAX elicitin. The BAX-induced cell death was scored at 3 and 4 DAI. A. tumefaciens strain carrying pGR106-GFP was used as a negative control, and pGR106-BAX as a positive control. (B) Western blot analysis of GFP, Iug6, Iug9, Nup1, Nup2, Nup3, and Bax protein levels in plant tissues treated above. Proteins were extracted 60 h after the last infiltration. Equal amounts of protein lysate were loaded in each lane, as verified by Ponceau S staining. (C) Presence or absence polymorphisms of each candidate effectors are indicated by a colored or black tile across the 29 field isolates. Colored tile, presence; black tile, absence. Presence /absence patterns (top) and isolates (left) were hierarchically clustered.

Mentions: To identify Iug6 and Iug9 functions, we used a PVX-based high-throughput transient plant expression system in Nicotiana benthamiana. We also included three randomly selected non-specific proteins Nup1, Nup2, and Nup3 (MGG_07900, MGG_08024, and MGG_04546) for controls. We first removed the signal peptides of IUG6, IUG9, NUP1, NUP2, and NUP3 to enable the genes to be expressed stably in plant cells before cloning into the PVX vector pGR106. Infiltration of N. benthamiana leaves with Agrobacterium tumefaciens cells carrying pGR106:IUG6, pGR106:IUG9, pGR106:NUP1, pGR106:NUP2, pGR106:NUP3, and the negative control pGR106:GFP did not cause any obvious cell-death symptoms (S7 Fig), whereas obvious cell death was observed in N. benthamiana leaves infiltrated with A. tumefaciens cells carrying pGR106:BAX. N. benthamiana leaves infiltrated with A. tumefaciens cells harboring IUG6, IUG9, NUP1, NUP2, and NUP3 genes 24 h prior to infiltration with the pGR106:BAX-harboring cells did not produce symptoms (Fig 5A). The expression of BAX was detected at 48 h after infiltration (Fig 5B), which ruled out the possibility that BAX failed to express. Iug6, Iug9, Nup1, Nup2, and Nup3 all conferred BAX cell-death suppression activity. By analogy, additional effectors may also present in these 134 candidate effectors.


Global genome and transcriptome analyses of Magnaporthe oryzae epidemic isolate 98-06 uncover novel effectors and pathogenicity-related genes, revealing gene gain and lose dynamics in genome evolution.

Dong Y, Li Y, Zhao M, Jing M, Liu X, Liu M, Guo X, Zhang X, Chen Y, Liu Y, Liu Y, Ye W, Zhang H, Wang Y, Zheng X, Wang P, Zhang Z - PLoS Pathog. (2015)

Iug6, Iug9, Nup1, Nup2, and Nup3 suppress the cell death triggered by BAX.(A) Agroinfiltration sites in N. benthamiana leaves expressing Iug6, Iug9, Nup1, Nup2, or Nup3 were challenged with A. tumefaciens expressing the BAX elicitin. The BAX-induced cell death was scored at 3 and 4 DAI. A. tumefaciens strain carrying pGR106-GFP was used as a negative control, and pGR106-BAX as a positive control. (B) Western blot analysis of GFP, Iug6, Iug9, Nup1, Nup2, Nup3, and Bax protein levels in plant tissues treated above. Proteins were extracted 60 h after the last infiltration. Equal amounts of protein lysate were loaded in each lane, as verified by Ponceau S staining. (C) Presence or absence polymorphisms of each candidate effectors are indicated by a colored or black tile across the 29 field isolates. Colored tile, presence; black tile, absence. Presence /absence patterns (top) and isolates (left) were hierarchically clustered.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383609&req=5

ppat.1004801.g005: Iug6, Iug9, Nup1, Nup2, and Nup3 suppress the cell death triggered by BAX.(A) Agroinfiltration sites in N. benthamiana leaves expressing Iug6, Iug9, Nup1, Nup2, or Nup3 were challenged with A. tumefaciens expressing the BAX elicitin. The BAX-induced cell death was scored at 3 and 4 DAI. A. tumefaciens strain carrying pGR106-GFP was used as a negative control, and pGR106-BAX as a positive control. (B) Western blot analysis of GFP, Iug6, Iug9, Nup1, Nup2, Nup3, and Bax protein levels in plant tissues treated above. Proteins were extracted 60 h after the last infiltration. Equal amounts of protein lysate were loaded in each lane, as verified by Ponceau S staining. (C) Presence or absence polymorphisms of each candidate effectors are indicated by a colored or black tile across the 29 field isolates. Colored tile, presence; black tile, absence. Presence /absence patterns (top) and isolates (left) were hierarchically clustered.
Mentions: To identify Iug6 and Iug9 functions, we used a PVX-based high-throughput transient plant expression system in Nicotiana benthamiana. We also included three randomly selected non-specific proteins Nup1, Nup2, and Nup3 (MGG_07900, MGG_08024, and MGG_04546) for controls. We first removed the signal peptides of IUG6, IUG9, NUP1, NUP2, and NUP3 to enable the genes to be expressed stably in plant cells before cloning into the PVX vector pGR106. Infiltration of N. benthamiana leaves with Agrobacterium tumefaciens cells carrying pGR106:IUG6, pGR106:IUG9, pGR106:NUP1, pGR106:NUP2, pGR106:NUP3, and the negative control pGR106:GFP did not cause any obvious cell-death symptoms (S7 Fig), whereas obvious cell death was observed in N. benthamiana leaves infiltrated with A. tumefaciens cells carrying pGR106:BAX. N. benthamiana leaves infiltrated with A. tumefaciens cells harboring IUG6, IUG9, NUP1, NUP2, and NUP3 genes 24 h prior to infiltration with the pGR106:BAX-harboring cells did not produce symptoms (Fig 5A). The expression of BAX was detected at 48 h after infiltration (Fig 5B), which ruled out the possibility that BAX failed to express. Iug6, Iug9, Nup1, Nup2, and Nup3 all conferred BAX cell-death suppression activity. By analogy, additional effectors may also present in these 134 candidate effectors.

Bottom Line: A unique 1.4 Mb of genomic sequences was found in isolate 98-06 in comparison to reference strain 70-15.In addition, 134 candidate effectors with various segregation patterns were identified.Characterization of isolate-specific effector candidates Iug6 and Iug9 and PaR candidate Iug18 revealed that they have a role in fungal propagation and pathogenicity.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, China; Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China.

ABSTRACT
Genome dynamics of pathogenic organisms are driven by pathogen and host co-evolution, in which pathogen genomes are shaped to overcome stresses imposed by hosts with various genetic backgrounds through generation of a variety of isolates. This same principle applies to the rice blast pathogen Magnaporthe oryzae and the rice host; however, genetic variations among different isolates of M. oryzae remain largely unknown, particularly at genome and transcriptome levels. Here, we applied genomic and transcriptomic analytical tools to investigate M. oryzae isolate 98-06 that is the most aggressive in infection of susceptible rice cultivars. A unique 1.4 Mb of genomic sequences was found in isolate 98-06 in comparison to reference strain 70-15. Genome-wide expression profiling revealed the presence of two critical expression patterns of M. oryzae based on 64 known pathogenicity-related (PaR) genes. In addition, 134 candidate effectors with various segregation patterns were identified. Five tested proteins could suppress BAX-mediated programmed cell death in Nicotiana benthamiana leaves. Characterization of isolate-specific effector candidates Iug6 and Iug9 and PaR candidate Iug18 revealed that they have a role in fungal propagation and pathogenicity. Moreover, Iug6 and Iug9 are located exclusively in the biotrophic interfacial complex (BIC) and their overexpression leads to suppression of defense-related gene expression in rice, suggesting that they might participate in biotrophy by inhibiting the SA and ET pathways within the host. Thus, our studies identify novel effector and PaR proteins involved in pathogenicity of the highly aggressive M. oryzae field isolate 98-06, and reveal molecular and genomic dynamics in the evolution of M. oryzae and rice host interactions.

No MeSH data available.


Related in: MedlinePlus