MAP Kinase and Protein Kinase A–Dependent Mobilization of Triacylglycerol and Glycogen during Appressorium Turgor Generation by <i>Magnaporthe grisea</i>

Thines, Eckhard; Weber, Roland W.S.; Talbot, Nicholas J.

doi:10.1105/tpc.12.9.1703

Cited by 320 publications

(337 citation statements)

References 57 publications

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“…M. grisea also seems to have the capacity to synthesize glycerol from the glycolytic intermediates dihydroxyacetone phosphate and dihydroxyacetone. Activity of both NADH-dependent glycerol-3-phosphate dehydrogenase and NADPH-dependent glycerol dehydrogenase has been reported in developing appressoria of M. grisea 24 . Taken together, the apparent flexibility in lipid metabolism and ability to divert intermediates from glycolysis may be important for rapid glycerol accumulation during appressorium development.…”

Section: Grisea Has a Family Of Novel G-protein-coupled Receptorsmentioning

confidence: 99%

The genome sequence of the rice blast fungus Magnaporthe grisea

Dean

Talbot

Ebbole

et al. 2005

Nature

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Magnaporthe grisea is the most destructive pathogen of rice worldwide and the principal model organism for elucidating the molecular basis of fungal disease of plants. Here, we report the draft sequence of the M. grisea genome. Analysis of the gene set provides an insight into the adaptations required by a fungus to cause disease. The genome encodes a large and diverse set of secreted proteins, including those defined by unusual carbohydrate-binding domains. This fungus also possesses an expanded family of G-protein-coupled receptors, several new virulence-associated genes and large suites of enzymes involved in secondary metabolism. Consistent with a role in fungal pathogenesis, the expression of several of these genes is upregulated during the early stages of infection-related development. The M. grisea genome has been subject to invasion and proliferation of active transposable elements, reflecting the clonal nature of this fungus imposed by widespread rice cultivation.Outbreaks of rice blast disease are a serious and recurrent problem in all rice-growing regions of the world, and the disease is extremely difficult to control 1,2 . Rice blast, caused by the fungus Magnaporthe grisea, is therefore a significant economic and humanitarian problem. It is estimated that each year enough rice is destroyed by rice blast disease to feed 60 million people 3 . The life cycle of the rice blast fungus is shown in Fig. 1. Infections occur when fungal spores land and attach themselves to leaves using a special adhesive released from the tip of each spore 4 . The germinating spore develops an appressorium-a specialized infection cell-which generates enormous turgor pressure (up to 8 MPa) that ruptures the leaf cuticle, allowing invasion of the underlying leaf tissue 5,6 . Subsequent colonization of the leaf produces disease lesions from which the fungus sporulates and spreads to new plants. When rice blast infects young rice seedlings, whole plants often die, whereas spread of the disease to the stems, nodes or panicle of older plants results in nearly total loss of the rice grain 2 . Different host-limited forms of M. grisea also infect a broad range of grass species including wheat, barley and millet. Recent reports have shown that the fungus has the capacity to infect plant roots 7 .Here we present our preliminary analysis of the draft genome sequence of M. grisea, which has emerged as a model system for understanding plant-microbe interactions because of both its economic significance and genetic tractability 1,2 . Acquisition of the M. grisea genome sequenceThe genome of a rice pathogenic strain of M. grisea, 70-15, was sequenced through a whole-genome shotgun approach. In all, greater than sevenfold sequence coverage was produced, and a summary of the principal genome sequence data is provided in Table 1 and Supplementary Table S1. The draft genome sequence consists of 2,273 sequence contigs longer than 2 kilobases (kb), ordered and orientated within 159 scaffolds. The total length of all sequence contigs is 38.8 mega...

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Section: Grisea Has a Family Of Novel G-protein-coupled Receptorsmentioning

confidence: 99%

The genome sequence of the rice blast fungus Magnaporthe grisea

Dean

Talbot

Ebbole

et al. 2005

Nature

Self Cite

1,500

1,194

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“…The first stage of the infection cycle begins on the leaf surface where the fungus is reliant on the catabolism of intracellular nutrient sources for germination and growth prior to penetration (Idnurm & Howlett, 2002;Solomon et al, 2004;Thines et al, 2000). The second phase of the infection cycle begins after the fungus has penetrated the host and initiates a period of vegetative growth whilst accessing the rich carbon and nitrogen sources (Solomon & Oliver, 2001).…”

Section: Introductionmentioning

confidence: 99%

δ-Aminolaevulinic acid synthesis is required for virulence of the wheat pathogen Stagonospora nodorum

2006

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d-Aminolaevulinic acid (ALA) is synthesized in fungi by ALA synthase, a key enzyme in the synthesis of haem. The requirement for ALA synthase in Stagonospora nodorum to cause disease in wheat was investigated. The single gene encoding ALA synthase (Als1) was cloned and characterized. Expression analysis determined that Als1 transcription was up-regulated during germination and also towards the latter stages of the infection. The Als1 gene was further characterized by homologous gene replacement. The inactivation of Als1 resulted in strains producing severely stunted germ tubes leading quickly to death. The strains could be recovered by supplementation with 33 mM ALA. Pathogenicity assays revealed the als1 strains were essentially non-pathogenic, inferring a key role for the synthesis of ALA during in planta growth. Supplementing the strains with ALA restored growth in vitro and also pathogenicity for up to 5 days after inoculation. Further examination by inoculating the als1 strains onto wounded leaves found that pathogenicity was only partially restored, suggesting that host-derived in planta levels of ALA are not sufficient to support growth. This study has identified a key role for fungal ALA synthesis during infection and revealed its potential as an antifungal target.

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“…Glycerol can be synthesized from several of the intermediates in this pathway. Unfortunately, we did not identify any putative homologues in the M. haptotylum EST database of enzymes known to be involved in these pathways in S. cerevisiae (see references in Thines et al, 2000). Thus, whether or not the genes encoding these enzymes are regulated in the knobs is not known.…”

Section: Glycogen and Carbon Metabolismmentioning

confidence: 96%

“…grisea, but is rapidly degraded before generating the turgor pressure needed for penetration of the plant cuticle (Thines et al, 2000). The turgor pressure results from a rapid accumulation of glycerol, and there are different lines of evidence suggesting that the production of glycerol is achieved by the mobilization of energy reserves, such as glycogen and neutral lipids (Thines et al, 2000). The glucose 1-phosphate generated from the degradation of glycogen is metabolized in the glycolytic pathway.…”

Section: Glycogen and Carbon Metabolismmentioning

confidence: 99%

Comparison of gene expression in trap cells and vegetative hyphae of the nematophagous fungus Monacrosporium haptotylum

et al. 2005

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Nematode-trapping fungi enter the parasitic stage by developing specific morphological structures called traps. The global patterns of gene expression in traps and mycelium of the fungus Monacrosporium haptotylum were compared. The trap of this fungus is a unicellular spherical structure called the knob, which develops on the apex of a hyphal branch. RNA was isolated from knobs and mycelium and hybridized to a cDNA array containing probes of 2822 EST clones of M. haptotylum. Despite the fact that the knobs and mycelium were grown in the same medium, there were substantial differences in the patterns of genes expressed in the two cell types. In total, 23?3 % (657 of 2822) of the putative genes were differentially expressed in knobs versus mycelium. Several of these genes displayed sequence similarities to genes known to be involved in regulating morphogenesis and cell polarity in fungi. Among them were several putative homologues for small GTPases, such as rho1, rac1 and ras1, and a rho GDP dissociation inhibitor (rdi1). Several homologues to genes involved in stress response, protein synthesis and protein degradation, transcription, and carbon metabolism were also differentially expressed. In the last category, a glycogen phosphorylase (gph1) gene homologue, one of the most upregulated genes in the knobs as compared to mycelium, was characterized. A number of the genes that were differentially expressed in trap cells are also known to be regulated during the development of infection structures in plant-pathogenic fungi. Among them, a gas1 (mas3) gene homologue (designated gks1), which is specifically expressed in appressoria of the rice blast fungus, was characterized.

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MAP Kinase and Protein Kinase A–Dependent Mobilization of Triacylglycerol and Glycogen during Appressorium Turgor Generation by Magnaporthe grisea

Cited by 320 publications

References 57 publications

The genome sequence of the rice blast fungus Magnaporthe grisea

The genome sequence of the rice blast fungus Magnaporthe grisea

δ-Aminolaevulinic acid synthesis is required for virulence of the wheat pathogen Stagonospora nodorum

Comparison of gene expression in trap cells and vegetative hyphae of the nematophagous fungus Monacrosporium haptotylum

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