Yanhan Dong

Nanjing Agricultural University, Nan-ching, Jiangsu Sheng, China

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Publications (6)25.81 Total impact

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    ABSTRACT: The rice blast fungus Magnaporthe oryzae encodes eight regulators of G-protein signaling (RGS) proteins MoRgs1-MoRgs8 that orchestrate the growth, asexual/sexual production, appressorium differentiation, and pathogenicity. To address the mechanisms by which MoRgs proteins function, we conducted a two-dimensional electrophoresis (2-DE) proteome study and identified 82 differentially expressed proteins by comparing five ∆Morgs mutants with wild type Guy11 strain. We found that the abundances of eight amino acid biosynthesis or degradation-associated proteins were markedly altered in five ∆Morgs mutants, indicating one of the main collective roles for the MoRgs proteins is to influence amino acid metabolism. We showed that MoRgs proteins have distinct roles in amino acid metabolism and nutrient responses from growth assays. In addition, we characterized MoLys20, a homocitrate synthase, whose abundance was significantly decreased in the ∆Morgs mutants. The ∆Molys20 mutant is auxotrophic for lysine and exogenous lysine could partially rescue its auxotrophic defects. Deletion of MoLYS20 resulted in defects in conidiation and infection, as well as pathogenicity on rice. Overall, our results indicate that one of the critical roles for MoRgs proteins is to regulate amino acid metabolism, and that MoLys20 may be directly or indirectly regulated by MoRgs and participated in lysine biosynthesis, thereby affecting fungal development and pathogenicity. This article is protected by copyright. All rights reserved.
    Proteomics 09/2014; · 4.43 Impact Factor
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    ABSTRACT: Amino acid biosyntheses are complex but essential processes in growth and differentiation of eukaryotic cells. In the budding yeast Saccharomyces cerevisiae, the lysine biosynthesis via the α-aminoadipate (AA) pathway involves several steps, including reduction of AA to AA 6-semialdehyde by AA reductase ScLys2. In filamentous fungus Penicillium chrysogenum, disruption of the LYS2 gene blocked the lysine biosynthesis but promoted the production of the secondary metabolite penicillin. In comparison, little is known about the function of AA reductase Lys2 in phytopathogenic fungi. We here characterized the functions of MoLys2, a homolog of ScLys2, from the rice blast fungus Magnaporthe oryzae. Our results showed that the ΔMolys2 mutants were auxotrophic for lysine. The ΔMolys2 mutants also exhibited drastic reduction in pathogenicity on rice, inducing small disease lesions. Microscopic examination of the lesions revealed that the invasive hyphae of ΔMolys2 mutants were mostly restricted to the primary infected leaf sheath cells. In addition, exogenous lysine restored the production of conidia and near wild-type appressoria differentiation, and rescued the defect of pathogenicity in conidia infection of detached barely and rice leaf sheath. Our results indicated that MoLys2 is necessary for lysine biosynthesis that affects growth, conidiogenesis, and pathogenicity of the fungus. This study does implicate the potential for targeting lysine biosynthesis for the development of novel fungicides against M. oryzae.
    Fungal Genetics and Biology 04/2014; · 3.26 Impact Factor
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    ABSTRACT: The mitogen activated protein kinase MoOsm1-mediated osmoregulation pathway plays crucial roles in stress responses, asexual/sexual development, and pathogenicity in Magnaporthe oryzae. Utilizing an affinity purification approach, we identified the putative transcriptional activator MoMsn2 as a protein that interacts with MoOsm1 in vivo. Disruption of the MoMSN2 gene resulted in defects in aerial hyphal growth, conidial production, and infection of host plants. Quantitative RT-PCR analysis showed that the expression of several genes involved in conidiophore formation was reduced in ∆Momsn2, suggesting that MoMsn2 might function as a transcriptional regulator of these genes. Subsequently, MoCos1 was identified as one of the MoMsn2 targets through yeast one hybrid analysis in which MoMsn2 binds to the AGGGG and CCCCT motif of the MoCOS1 promoter region. Phenotypic characterization showed that MoMsn2 was required for appressorium formation and penetration, and pathogenicity. Although the ∆Momsn2 mutant was tolerant to the cell wall stressor Calcofluor white, it was sensitive to common osmotic stressors. Further analysis suggests that MoMsn2 is involved in the regulation of the cell wall biosynthesis pathway. Finally, transcriptome data revealed that MoMsn2 modulates numerous genes participating in conidiation, infection, cell wall integrity, and stress response. Collectively, our results led to a model that MoMsn2 mediates a series of downstream genes to control aerial hyphal growth, conidiogenesis, appressorium formation, cell wall biosynthesis, and infection and also offer potential targets for the development of new disease management strategies.
    Molecular Plant-Microbe Interactions 01/2014; · 4.31 Impact Factor
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    ABSTRACT: Amino acid biosyntheses are complex but essential processes in growth and differentiation of eukaryotic cells. In the budding yeast Saccharomyces cerevisiae, the lysine biosynthesis via the α-aminoadipate (AA) pathway involves several steps, including reduction of AA to AA 6-semialdehyde by AA reductase ScLys2. In filamentous fungus Penicillium chrysogenum, disruption of the LYS2 gene blocked the lysine biosynthesis but promoted the production of the secondary metabolite penicillin. In comparison, little is known about the function of AA reductase Lys2 in phytopathogenic fungi. We here characterized the functions of MoLys2, a homolog of ScLys2, from the rice blast fungus Magnaporthe oryzae. Our results showed that the ΔMolys2 mutants were auxotrophic for lysine. The ΔMolys2 mutants also exhibited drastic reduction in pathogenicity on rice, inducing small disease lesions. Microscopic examination of the lesions revealed that the invasive hyphae of ΔMolys2 mutants were mostly restricted to the primary infected leaf sheath cells. In addition, exogenous lysine restored the production of conidia and near wild-type appressoria differentiation, and rescued the defect of pathogenicity in conidia infection of detached barely and rice leaf sheath. Our results indicated that MoLys2 is necessary for lysine biosynthesis that affects growth, conidiogenesis, and pathogenicity of the fungus. This study does implicate the potential for targeting lysine biosynthesis for the development of novel fungicides against M. oryzae.
    Fungal Genetics and Biology 01/2014; · 3.26 Impact Factor
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    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.
    PLoS Pathogens 02/2011; 7(2):e1001302. · 8.14 Impact Factor
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    ABSTRACT: A two-component signal transduction system is a common mechanism for environmental sensing in bacteria. The functions of the two-component molecules have been also well characterized in the lower eukaryotic fungi in recent years. In Saccharomyces cerevisiae, the histidine kinase Sln1p is a major component of the two-component signaling pathways and a key regulator of the osmolarity response. To determine the function of MoSLN1, a Sln1 homolog of Magnaporthe oryzae, we cloned the MoSLN1 gene and generated specific mutants using gene knock-out strategy. Disruption of MoSLN1 resulted in hypersensitivity to various stresses, reduced sensitivity to cell wall perturbing agent Calcofluor white, and loss of pathogenicity, mainly due to a penetration defect. Additionally, we showed that MoSLN1 is involved in oxidative signaling through modulation of intra- and extracellular peroxidase activities. These results indicate that MoSLN1 functions as a pathogenicity factor that plays a role in responses to osmotic stress, the cell wall integrity, and the activity of peroxidases.
    Current Genetics 12/2010; 56(6):517-28. · 2.41 Impact Factor