Oh, Y. et al. Transcriptome analysis reveals new insight into appressorium formation and function in the rice blast fungus Magnaporthe oryzae. Genome Biol. 9, R85

North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA.
Genome biology (Impact Factor: 10.81). 02/2008; 9(5):R85. DOI: 10.1186/gb-2008-9-5-r85
Source: PubMed


Rice blast disease is caused by the filamentous Ascomycetous fungus Magnaporthe oryzae and results in significant annual rice yield losses worldwide. Infection by this and many other fungal plant pathogens requires the development of a specialized infection cell called an appressorium. The molecular processes regulating appressorium formation are incompletely understood.
We analyzed genome-wide gene expression changes during spore germination and appressorium formation on a hydrophobic surface compared to induction by cAMP. During spore germination, 2,154 (approximately 21%) genes showed differential expression, with the majority being up-regulated. During appressorium formation, 357 genes were differentially expressed in response to both stimuli. These genes, which we refer to as appressorium consensus genes, were functionally grouped into Gene Ontology categories. Overall, we found a significant decrease in expression of genes involved in protein synthesis. Conversely, expression of genes associated with protein and amino acid degradation, lipid metabolism, secondary metabolism and cellular transportation exhibited a dramatic increase. We functionally characterized several differentially regulated genes, including a subtilisin protease (SPM1) and a NAD specific glutamate dehydrogenase (Mgd1), by targeted gene disruption. These studies revealed hitherto unknown findings that protein degradation and amino acid metabolism are essential for appressorium formation and subsequent infection.
We present the first comprehensive genome-wide transcript profile study and functional analysis of infection structure formation by a fungal plant pathogen. Our data provide novel insight into the underlying molecular mechanisms that will directly benefit efforts to identify fungal pathogenicity factors and aid the development of new disease management strategies.

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    • "This pathway is fungus specific, and the ergosterol is required for the generation of a major constituent of the fungal plasma membrane (Parks and Casey 1995). The ergosterol biosynthesis is via the mevalonate pathway, in which the ERG13 (HMG-CoA synthase) and HMG1 (HMG-CoA reductase) catalyze two key consecutive steps for the conversion of acetoacetyl-CoA to HMG-CoA and HMG-CoA to mevalonate, respectively (Oh et al. 2008). As critical components of cell membranes of all eukaryotic organisms, steroid is required for the regulation of membrane fluidity and permeability (Lepesheva and Waterman 2007). "
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    ABSTRACT: Conidial germination is a crucial step of the soilborne fungus Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), a most important lethal disease of banana. In this study, a total of 3659 proteins were identified by isobaric tags for relative and absolute quantitation (iTRAQ)-based comparative proteomic approach, of which 1009 were differentially expressed during conidial germination of the fungus at 0, 3, 7, and 11 h. Functional classification and bioinformatics analysis revealed that the majority of the differentially expressed proteins are involved in six metabolic pathways. Particularly, all differential proteins involved in the ergosterol biosynthesis pathway were significantly upregulated, indicating the importance of the ergosterol biosynthesis pathway to the conidial germination of Foc TR4. Quantitative RT-PCR, western blotting, and in vitro growth inhibition assay by several categories of fungicides on the Foc TR4 were used to validate the proteomics results. Four enzymes, C-24 sterol methyltransferase (ERG6), cytochrome P450 lanosterol C-14α-demethylase (EGR11), hydroxymethylglutaryl-CoA synthase (ERG13), and C-4 sterol methyl oxidase (ERG25), in the ergosterol biosynthesis pathway were identified and verified, and they hold great promise as new targets for effective inhibition of Foc TR4 early growth in controlling Fusarium wilt of banana. To the best of our knowledge, this report represents the first comprehensive study on proteomics profiling of conidia germination in Foc TR4. It provides new insights into a better understanding of the developmental processes of Foc TR4 spores. More importantly, by host plant-induced gene silencing (HIGS) technology, the new targets reported in this work allow us to develop novel transgenic banana leading to high protection from Fusarium wilt and to explore more effective antifungal drugs against either individual or multiple target proteins of Foc TR4.
    Applied Microbiology and Biotechnology 07/2015; 99(17). DOI:10.1007/s00253-015-6768-x · 3.34 Impact Factor
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    • "No such expression pattern was not observed for transcripts encoding CRN proteins, suggesting different roles for these two classes of cytoplasmic effectors. Previous studies reported the detection of transcripts encoding secreted effectors in appressoria from Phytophthora species such as P. infestans, P. sojae, and P. capsici and in appressoria from ascomycetes, such as Magnaporthe grisea and Colletotrichum higginsianum [19, 21, 40, 41]. However, the secretion of Phytophthora cytoplasmic effectors has been documented only in haustoria to date. "
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    BMC Genomics 06/2014; 15(1):538. DOI:10.1186/1471-2164-15-538 · 3.99 Impact Factor
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    • "). Furthermore, several of these transporters are up-regulated during appressorium formation (Oh et al., 2008), under stress treatments or in planta (Mathioni et al., 2011), and are required for pathogenicity (Urban et al., 1999; Sun et al., 2006; Patkar et al., 2012b), possibly to protect against the buildup of peroxides and oxidative damage (Sun et al., 2006). Given our concerns over H 2 DCFDA localization and specificity , we also examined the more sensitive, specific and photostable long-wavelength ROS probe CRDR. "
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    ABSTRACT: Plants respond to pathogen attack via a rapid burst of reactive oxygen species (ROS). However, ROS are also produced by fungal metabolism and are required for the development of infection structures in Magnaporthe oryzae. To obtain a better understanding of redox regulation in M. oryzae, we measured the amount and redox potential of glutathione (EGSH ), as the major cytoplasmic anti-oxidant, the rates of ROS production, and mitochondrial activity using multi-channel four-dimensional (x,y,z,t) confocal imaging of Grx1-roGFP2 and fluorescent reporters during spore germination, appressorium formation and infection. High levels of mitochondrial activity and ROS were localized to the growing germ tube and appressorium, but EGSH was highly reduced and tightly regulated during development. Furthermore, germlings were extremely resistant to external H2 O2 exposure ex planta. EGSH remained highly reduced during successful infection of the susceptible rice cultivar CO39. By contrast, there was a dramatic reduction in the infection of resistant (IR68) rice, but the sparse hyphae that did form also maintained a similar reduced EGSH . We conclude that M. oryzae has a robust anti-oxidant defence system and maintains tight control of EGSH despite substantial oxidative challenge. Furthermore, the magnitude of the host oxidative burst alone does not stress the pathogen sufficiently to prevent infection in this pathosystem.
    New Phytologist 10/2013; 201(2). DOI:10.1111/nph.12530 · 7.67 Impact Factor
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