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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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Pathogenicity test of Mossadh and Moact mutant strains on the wounded rice leaves.(A) Pathogenicity test of Mossadh mutants on the wounded rice leaves. The mycelia blocks of the wild type strain Guy11, Mossadh mutants, and the complemented strain were inoculated on the wounded rice leaves and then cultured under moist conditions with 28°C for 5 days. The wounded rice leaves with the CM agar plugs on was used as negative control. This experiment was performed three times with 10 pieces of rice leaves for each strain. Similar results were obtained in each test and this picture showed the representative result. (B) Pathogenicity test of Moact mutants on the wounded rice leaves. The mycelia blocks of Guy11, Moact mutants and the complemented strain were inoculated on the wounded rice leaves and observations made as above. (C) Pathogenicity test of the mutant strain by injection of hyphae fragments. The hyphae fragments of Guy11, the mutant strains and respective complemented strains were prepared as described in Materials and Methods. From left to right, leaves injected with water, wild type strain, Mossadh mutant, and Moact mutant. The arrowheads in black indicate injection sites with necrosis, while the arrowheads in white indicate injection sites without necrosis.
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ppat-1001302-g010: Pathogenicity test of Mossadh and Moact mutant strains on the wounded rice leaves.(A) Pathogenicity test of Mossadh mutants on the wounded rice leaves. The mycelia blocks of the wild type strain Guy11, Mossadh mutants, and the complemented strain were inoculated on the wounded rice leaves and then cultured under moist conditions with 28°C for 5 days. The wounded rice leaves with the CM agar plugs on was used as negative control. This experiment was performed three times with 10 pieces of rice leaves for each strain. Similar results were obtained in each test and this picture showed the representative result. (B) Pathogenicity test of Moact mutants on the wounded rice leaves. The mycelia blocks of Guy11, Moact mutants and the complemented strain were inoculated on the wounded rice leaves and observations made as above. (C) Pathogenicity test of the mutant strain by injection of hyphae fragments. The hyphae fragments of Guy11, the mutant strains and respective complemented strains were prepared as described in Materials and Methods. From left to right, leaves injected with water, wild type strain, Mossadh mutant, and Moact mutant. The arrowheads in black indicate injection sites with necrosis, while the arrowheads in white indicate injection sites without necrosis.

Mentions: The results above indicated that Mossadh and Moact mutants lost the ability to penetrate the plant cell. If these results are the main reason for the lost pathogenicity, given the conditions, abraded rice leaves should restore pathogenicity to the mutants. To examine this, we inoculated wounded rice leaves with agar plugs containing mycelial tips to evaluate pathogenicity. Both the Mossadh and Moact mutants were unable to cause symptoms, while the wild-type strain produced visible diffuse lesions on rice leaves 5 days after inoculation (Figure 10A and 10B). The similar result was found when the observation was made at 7 days post infection (dpi) (see Figure S9B).


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)

Pathogenicity test of Mossadh and Moact mutant strains on the wounded rice leaves.(A) Pathogenicity test of Mossadh mutants on the wounded rice leaves. The mycelia blocks of the wild type strain Guy11, Mossadh mutants, and the complemented strain were inoculated on the wounded rice leaves and then cultured under moist conditions with 28°C for 5 days. The wounded rice leaves with the CM agar plugs on was used as negative control. This experiment was performed three times with 10 pieces of rice leaves for each strain. Similar results were obtained in each test and this picture showed the representative result. (B) Pathogenicity test of Moact mutants on the wounded rice leaves. The mycelia blocks of Guy11, Moact mutants and the complemented strain were inoculated on the wounded rice leaves and observations made as above. (C) Pathogenicity test of the mutant strain by injection of hyphae fragments. The hyphae fragments of Guy11, the mutant strains and respective complemented strains were prepared as described in Materials and Methods. From left to right, leaves injected with water, wild type strain, Mossadh mutant, and Moact mutant. The arrowheads in black indicate injection sites with necrosis, while the arrowheads in white indicate injection sites without necrosis.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1001302-g010: Pathogenicity test of Mossadh and Moact mutant strains on the wounded rice leaves.(A) Pathogenicity test of Mossadh mutants on the wounded rice leaves. The mycelia blocks of the wild type strain Guy11, Mossadh mutants, and the complemented strain were inoculated on the wounded rice leaves and then cultured under moist conditions with 28°C for 5 days. The wounded rice leaves with the CM agar plugs on was used as negative control. This experiment was performed three times with 10 pieces of rice leaves for each strain. Similar results were obtained in each test and this picture showed the representative result. (B) Pathogenicity test of Moact mutants on the wounded rice leaves. The mycelia blocks of Guy11, Moact mutants and the complemented strain were inoculated on the wounded rice leaves and observations made as above. (C) Pathogenicity test of the mutant strain by injection of hyphae fragments. The hyphae fragments of Guy11, the mutant strains and respective complemented strains were prepared as described in Materials and Methods. From left to right, leaves injected with water, wild type strain, Mossadh mutant, and Moact mutant. The arrowheads in black indicate injection sites with necrosis, while the arrowheads in white indicate injection sites without necrosis.
Mentions: The results above indicated that Mossadh and Moact mutants lost the ability to penetrate the plant cell. If these results are the main reason for the lost pathogenicity, given the conditions, abraded rice leaves should restore pathogenicity to the mutants. To examine this, we inoculated wounded rice leaves with agar plugs containing mycelial tips to evaluate pathogenicity. Both the Mossadh and Moact mutants were unable to cause symptoms, while the wild-type strain produced visible diffuse lesions on rice leaves 5 days after inoculation (Figure 10A and 10B). The similar result was found when the observation was made at 7 days post infection (dpi) (see Figure S9B).

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