Publications (8)11.9 Total impact
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ABSTRACT: The Magnaporthe oryzae mitogen-activated protein kinase (MAPK) MoMps1 plays a critical role in the regulation of various developmental processes, including cell wall integrity, stress responses and pathogenicity. To identify potential effectors of MoMps1, we characterized the function of MoSwi6, a homologue of Saccharomyces cerevisiae Swi6 downstream of MAPK Slt2 signalling. MoSwi6 interacted with MoMps1 both in vivo and in vitro, suggesting a possible functional link analogous to Swi6-Slt2 in S. cerevisiae. Targeted gene disruption of MoSWI6 resulted in multiple developmental defects, including reduced hyphal growth, abnormal formation of conidia and appressoria, and impaired appressorium function. The reduction in appressorial turgor pressure also contributed to an attenuation of pathogenicity. The ΔMoswi6 mutant also displayed a defect in cell wall integrity, was hypersensitive to oxidative stress, and showed a significant reduction in transcription and activity of extracellular enzymes, including peroxidases and laccases. Collectively, these roles are similar to those of MoMps1, confirming that MoSwi6 functions in the MoMps1 pathway to govern growth, development and full pathogenicity.
Dataset: Figure S6[Show abstract] [Hide abstract]
ABSTRACT: Radial growth of ΔMoglk1 and ΔMohxk1 mutants on GMM with 100 mM glutamate. Photographs (A) were taken from one transformant of each mutant at indicated days after incubation at 30°C. Colony diameter (B) were measured at the same days. The experiment was performed with three strains for the ΔMoglk1 and ΔMohxk1 mutants, respectively; and three independent replicates provided the same results. Different letter represent difference among (P<0.05) among Guy11 and ΔMoglk1, ΔMohxk1. (TIF)
Dataset: Figure S4[Show abstract] [Hide abstract]
ABSTRACT: Complementation of S. cerevisiae Δhxk1Δhxk2Δglk1 triple mutant. Yeast cells transformed with plasmid pGBKT7 (control) containing MoGLK1 or MoHXK1 were cultured in YPEG medium to an OD600 of ∼1.0 at 30°C. Equal numbers of cells were spotted on YPEG or SD medium plates in the presence of glucose (Glc) or fructose (Fru) as the sole carbon source. Photographs were taken after culturing at 30°C for 4 days. 1 and 2 represent two independent yeast transformants containing MoGLK1 or MoHXK1 constructs. (TIF)
Dataset: Figure S5[Show abstract] [Hide abstract]
ABSTRACT: Radial growth of ΔMoglk1 and ΔMohxk1 mutants on GMM with 1 mM (A, B, and C) and 10 mM (D, E, and F) ammonium. Photographs (A and D) were taken from one transformant of each mutant at indicated days after incubation at 30°C. Colony diameter (B and E) and medium pH (C and F) were measured at the same days. The experiment was performed with three strains for the ΔMoglk1 and ΔMohxk1 mutants, respectively; and three independent replicates provided the same results. Different letter represent difference among (P<0.05) among Guy11 and ΔMoglk1, ΔMohxk1. (TIF)
Dataset: Figure S3[Show abstract] [Hide abstract]
ABSTRACT: Phylogenetic analysis of MoGLK1 and MoHXK1. Dendrogram showing the relationship of mammalian, plant, insect and fungal hexose kinases based on amino acid sequences. Sequences were obtained from GenBank. Numbers after genes correspond to Genbank accession numbers. The phylogenetic tree was generated by the neighbor-joining (NJ) method using Mega3.0 Beta. Branch lengths are drawn to scale. (TIF)
Dataset: Figure S2[Show abstract] [Hide abstract]
ABSTRACT: Alignment of MoGLK1, MoHXK1 and hexokinases and glucokinases in other fungi. The predicted amino acid sequences were aligned using Clustal W. The numbers indicated the amino acid residues. Gaps are indicated by dashes. Identical amino acids are highlighted on a black background, and similar amino acids on a light grey background. The hexokinase signature is marked by a single line. The black triangles indicate the key residues for catalytic activity. (TIF)
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ABSTRACT: Hexokinases are conserved proteins functioning in glucose sensing and signaling. The rice blast fungus Magnaporthe oryzae contains several hexokinases, including MoHxk1 (hexokinase) and MoGlk1 (glucokinase) encoded respectively by MoHXK1 and MoGLK1 genes. The heterologous expression of MoGlk1 and MoHxk1 in Saccharomyces cerevisiae confirmed their conserved functions. Disruption of MoHXK1 resulted in growth reduction in medium containing fructose as the sole carbon source, whereas disruption of MoGLK1 did not cause the similar defect. However, the ΔMoglk1 mutant displayed decreased proton extrusion and a lower biomass in the presence of ammonium, suggesting a decline in the utilization of ammonium. Additionally, the MoGLK1 allele lacking catalytic activity restored growth to the ΔMoglk1 mutant. Moreover, the expression of MoPMA1 encoding a plasma membrane H(+)-ATPase decreased in the ΔMoglk1 mutant that can be suppressed by glucose and G-6-P. Thus, MoGlk1, but not MoHxk1, regulates ammonium utilization through a mechanism that is independent from its catalytic activity.
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ABSTRACT: Magnaporthe oryzae is the causal agent of rice blast disease, leading to enormous losses of rice production. Here, we characterized a basic leucine zipper (bZIP) transcription factor, Moatf1, in M. oryzae, a homolog of Schizosaccharomyces pombe ATF/CREB that regulates the oxidative stress response. Moatf1 deletion caused retarded vegetative growth of mycelia, and the Moatf1 mutant exhibited higher sensitivity to hydrogen peroxide (H(2)O(2)) than did the wild-type strain. The mutant showed severely reduced activity of extracellular enzymes and transcription level of laccases and peroxidases and exhibited significantly reduced virulence on rice cultivar CO-39. On rice leaf sheath, most of the infectious hyphae of the mutant became swollen and displayed restricted growth in primary infected cells. Defense response was strongly activated in plants infected by the mutant. Diamino benzidine staining revealed an accumulation of H(2)O(2) around Moatf1 mutant appressoria and rice cells with Moatf1 hyphae that was absent in the wild type. Inhibition of the plant NADPH oxidase by diphenyleneiodonium prevented host-derived H(2)O(2) accumulation and restored infectious hyphal growth of the mutant in rice cells. Thus, we conclude that Moatf1 is necessary for full virulence of M. oryzae by regulating the transcription of laccases and peroxidases to impair reactive oxygen species-mediated plant defense.
Nanjing Agricultural University
Nan-ching, Jiangsu Sheng, China
- Department of Plant Pathology