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The bZIP transcription factor MoAP1 mediates the oxidative stress response and is critical for pathogenicity of the rice blast fungus Magnaporthe oryzae.

Guo M, Chen Y, Du Y, Dong Y, Guo W, Zhai S, Zhang H, Dong S, Zhang Z, Wang Y, Wang P, Zheng X - PLoS Pathog. (2011)

Bottom Line: We found that MoAP1 is highly expressed in conidia and during invasive hyphal growth.Disruption of respective MGG_01662 (MoAAT) and MGG_02531 (encoding hypothetical protein) genes did not result in any detectable changes in conidial germination and appressorium formation but reduced pathogenicity, whereas the mutant strains of MGG_01230 (MoSSADH) and MGG_15157 (MoACT) showed marketed reductions in aerial hyphal growth, mycelial branching, and loss of conidiation as well as pathogenicity, similar to the Moap1 mutant.Taken together, our studies identify MoAP1 as a positive transcription factor that regulates transcriptions of MGG_01662, MGG_02531, MGG_01230, and MGG_15157 that are important in the growth, development, and pathogenicity of M. oryzae.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China.

ABSTRACT
Saccharomyces cerevisiae Yap1 protein is an AP1-like transcription factor involved in the regulation of the oxidative stress response. An ortholog of Yap1, MoAP1, was recently identified from the rice blast fungus Magnaporthe oryzae genome. We found that MoAP1 is highly expressed in conidia and during invasive hyphal growth. The Moap1 mutant was sensitive to H₂O₂, similar to S. cerevisiae yap1 mutants, and MoAP1 complemented Yap1 function in resistance to H₂O₂, albeit partially. The Moap1 mutant also exhibited various defects in aerial hyphal growth, mycelial branching, conidia formation, the production of extracellular peroxidases and laccases, and melanin pigmentation. Consequently, the Moap1 mutant was unable to infect the host plant. The MoAP1-eGFP fusion protein is localized inside the nucleus upon exposure to H₂O₂, suggesting that MoAP1 also functions as a redox sensor. Moreover, through RNA sequence analysis, many MoAP1-regulated genes were identified, including several novel ones that were also involved in pathogenicity. Disruption of respective MGG_01662 (MoAAT) and MGG_02531 (encoding hypothetical protein) genes did not result in any detectable changes in conidial germination and appressorium formation but reduced pathogenicity, whereas the mutant strains of MGG_01230 (MoSSADH) and MGG_15157 (MoACT) showed marketed reductions in aerial hyphal growth, mycelial branching, and loss of conidiation as well as pathogenicity, similar to the Moap1 mutant. Taken together, our studies identify MoAP1 as a positive transcription factor that regulates transcriptions of MGG_01662, MGG_02531, MGG_01230, and MGG_15157 that are important in the growth, development, and pathogenicity of M. oryzae.

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Mossadh and Moact are hypersensitive to H2O2.(A) Phenotype of the Mossadh mutants under the oxidative stress. The wild type strain, Mossadh mutants and the complemented strain were inoculated on CM agar medium with or without 5 mM H2O2 and cultured at 28°C for 5 days. (B) Statistical analysis of mycelia growth rate with or without H2O2. The analysis was similar to Figure 3B. Error bars represent the standard deviations, and asterisks represent significant differences among Guy11, Mossadh mutants and the complemented strain (p<0.01). (C) Phenotype of the Moact mutant strains under the oxidative stress. Guy11, Moact mutants, and the complemented strain were inoculated on CM agar medium with or without 2 to 5 mM H2O2 and cultured at 28°C for 3 days. (D) Statistical analysis of mycelia growth. Error bars represent the standard deviations, and asterisks indicate that the differences among Guy11, Moact mutants and the complemented strain were statistically significant (p<0.01).
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ppat-1001302-g011: Mossadh and Moact are hypersensitive to H2O2.(A) Phenotype of the Mossadh mutants under the oxidative stress. The wild type strain, Mossadh mutants and the complemented strain were inoculated on CM agar medium with or without 5 mM H2O2 and cultured at 28°C for 5 days. (B) Statistical analysis of mycelia growth rate with or without H2O2. The analysis was similar to Figure 3B. Error bars represent the standard deviations, and asterisks represent significant differences among Guy11, Mossadh mutants and the complemented strain (p<0.01). (C) Phenotype of the Moact mutant strains under the oxidative stress. Guy11, Moact mutants, and the complemented strain were inoculated on CM agar medium with or without 2 to 5 mM H2O2 and cultured at 28°C for 3 days. (D) Statistical analysis of mycelia growth. Error bars represent the standard deviations, and asterisks indicate that the differences among Guy11, Moact mutants and the complemented strain were statistically significant (p<0.01).

Mentions: The stress-tolerance mechanisms of plant pathogens play an important role in virulence [14], [15], [59], [60]. To assess whether the putative MoAP1 targets MoSsadh and MoAct play an active role in the tolerance to exogenous H2O2, the mutant strains were inoculated on H2O2-containing CM medium. The assay results showed that both type of mutants were more sensitive to H2O2 than the wild-type strain (Figure 11A and 11C). The mycelial growth of the Mossadh mutant was severely inhibited on CM medium containing 5 mM H2O2, with 20% (Mossadh-4) and 17% (Mossadh-8) greater inhibition rates than the wild-type strain (Figure 11B). Meanwhile, the Moact mutants displayed higher sensitivity to H2O2 than either the Moap1 mutants or the Mossadh mutants, with an average 18% greater mycelial growth inhibition rate than the wild-type strain at 2 mM H2O2 and 61% at 5 mM H2O2. The sensitivity of the mutants to H2O2 was complemented by reintrodution of the respective wild type genes (Figure 11D).


The bZIP transcription factor MoAP1 mediates the oxidative stress response and is critical for pathogenicity of the rice blast fungus Magnaporthe oryzae.

Guo M, Chen Y, Du Y, Dong Y, Guo W, Zhai S, Zhang H, Dong S, Zhang Z, Wang Y, Wang P, Zheng X - PLoS Pathog. (2011)

Mossadh and Moact are hypersensitive to H2O2.(A) Phenotype of the Mossadh mutants under the oxidative stress. The wild type strain, Mossadh mutants and the complemented strain were inoculated on CM agar medium with or without 5 mM H2O2 and cultured at 28°C for 5 days. (B) Statistical analysis of mycelia growth rate with or without H2O2. The analysis was similar to Figure 3B. Error bars represent the standard deviations, and asterisks represent significant differences among Guy11, Mossadh mutants and the complemented strain (p<0.01). (C) Phenotype of the Moact mutant strains under the oxidative stress. Guy11, Moact mutants, and the complemented strain were inoculated on CM agar medium with or without 2 to 5 mM H2O2 and cultured at 28°C for 3 days. (D) Statistical analysis of mycelia growth. Error bars represent the standard deviations, and asterisks indicate that the differences among Guy11, Moact mutants and the complemented strain were statistically significant (p<0.01).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044703&req=5

ppat-1001302-g011: Mossadh and Moact are hypersensitive to H2O2.(A) Phenotype of the Mossadh mutants under the oxidative stress. The wild type strain, Mossadh mutants and the complemented strain were inoculated on CM agar medium with or without 5 mM H2O2 and cultured at 28°C for 5 days. (B) Statistical analysis of mycelia growth rate with or without H2O2. The analysis was similar to Figure 3B. Error bars represent the standard deviations, and asterisks represent significant differences among Guy11, Mossadh mutants and the complemented strain (p<0.01). (C) Phenotype of the Moact mutant strains under the oxidative stress. Guy11, Moact mutants, and the complemented strain were inoculated on CM agar medium with or without 2 to 5 mM H2O2 and cultured at 28°C for 3 days. (D) Statistical analysis of mycelia growth. Error bars represent the standard deviations, and asterisks indicate that the differences among Guy11, Moact mutants and the complemented strain were statistically significant (p<0.01).
Mentions: The stress-tolerance mechanisms of plant pathogens play an important role in virulence [14], [15], [59], [60]. To assess whether the putative MoAP1 targets MoSsadh and MoAct play an active role in the tolerance to exogenous H2O2, the mutant strains were inoculated on H2O2-containing CM medium. The assay results showed that both type of mutants were more sensitive to H2O2 than the wild-type strain (Figure 11A and 11C). The mycelial growth of the Mossadh mutant was severely inhibited on CM medium containing 5 mM H2O2, with 20% (Mossadh-4) and 17% (Mossadh-8) greater inhibition rates than the wild-type strain (Figure 11B). Meanwhile, the Moact mutants displayed higher sensitivity to H2O2 than either the Moap1 mutants or the Mossadh mutants, with an average 18% greater mycelial growth inhibition rate than the wild-type strain at 2 mM H2O2 and 61% at 5 mM H2O2. The sensitivity of the mutants to H2O2 was complemented by reintrodution of the respective wild type genes (Figure 11D).

Bottom Line: We found that MoAP1 is highly expressed in conidia and during invasive hyphal growth.Disruption of respective MGG_01662 (MoAAT) and MGG_02531 (encoding hypothetical protein) genes did not result in any detectable changes in conidial germination and appressorium formation but reduced pathogenicity, whereas the mutant strains of MGG_01230 (MoSSADH) and MGG_15157 (MoACT) showed marketed reductions in aerial hyphal growth, mycelial branching, and loss of conidiation as well as pathogenicity, similar to the Moap1 mutant.Taken together, our studies identify MoAP1 as a positive transcription factor that regulates transcriptions of MGG_01662, MGG_02531, MGG_01230, and MGG_15157 that are important in the growth, development, and pathogenicity of M. oryzae.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China.

ABSTRACT
Saccharomyces cerevisiae Yap1 protein is an AP1-like transcription factor involved in the regulation of the oxidative stress response. An ortholog of Yap1, MoAP1, was recently identified from the rice blast fungus Magnaporthe oryzae genome. We found that MoAP1 is highly expressed in conidia and during invasive hyphal growth. The Moap1 mutant was sensitive to H₂O₂, similar to S. cerevisiae yap1 mutants, and MoAP1 complemented Yap1 function in resistance to H₂O₂, albeit partially. The Moap1 mutant also exhibited various defects in aerial hyphal growth, mycelial branching, conidia formation, the production of extracellular peroxidases and laccases, and melanin pigmentation. Consequently, the Moap1 mutant was unable to infect the host plant. The MoAP1-eGFP fusion protein is localized inside the nucleus upon exposure to H₂O₂, suggesting that MoAP1 also functions as a redox sensor. Moreover, through RNA sequence analysis, many MoAP1-regulated genes were identified, including several novel ones that were also involved in pathogenicity. Disruption of respective MGG_01662 (MoAAT) and MGG_02531 (encoding hypothetical protein) genes did not result in any detectable changes in conidial germination and appressorium formation but reduced pathogenicity, whereas the mutant strains of MGG_01230 (MoSSADH) and MGG_15157 (MoACT) showed marketed reductions in aerial hyphal growth, mycelial branching, and loss of conidiation as well as pathogenicity, similar to the Moap1 mutant. Taken together, our studies identify MoAP1 as a positive transcription factor that regulates transcriptions of MGG_01662, MGG_02531, MGG_01230, and MGG_15157 that are important in the growth, development, and pathogenicity of M. oryzae.

Show MeSH
Related in: MedlinePlus