Gene Discovery and Gene Expression in the Rice Blast Fungus, <i>Magnaporthe grisea</i>: Analysis of Expressed Sequence Tags

Ebbole, Daniel J.; Jin, Yuan; Thon, Michael R.; Pan, Huaqin; Bhattarai, Eric K.; Thomas, Terry L.; Dean, Ralph A.

doi:10.1094/mpmi.2004.17.12.1337

Cited by 87 publications

(78 citation statements)

References 40 publications

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“…Screening of a cDNA subtraction library also identified GAS1 and GAS2, two Kss1-regulated genes encoding small proteins required for full appressorium function and virulence . Comparative analysis of ESTs obtained from wild-type appressoria and kss1 mutant germlings also revealed other potential genetic targets of this key MAPK (Ebbole et al, 2004). …”

Section: Mapks From Phytopathogenic Fungimentioning

confidence: 95%

Mitogen-Activated Protein Kinase Signaling in Plant-Interacting Fungi: Distinct Messages from Conserved Messengers

et al. 2012

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Mitogen-activated protein kinases (MAPKs) are evolutionarily conserved proteins that function as key signal transduction components in fungi, plants, and mammals. During interaction between phytopathogenic fungi and plants, fungal MAPKs help to promote mechanical and/or enzymatic penetration of host tissues, while plant MAPKs are required for activation of plant immunity. However, new insights suggest that MAPK cascades in both organisms do not operate independently but that they mutually contribute to a highly interconnected molecular dialogue between the plant and the fungus. As a result, some pathogenesis-related processes controlled by fungal MAPKs lead to the activation of plant signaling, including the recruitment of plant MAPK cascades. Conversely, plant MAPKs promote defense mechanisms that threaten the survival of fungal cells, leading to a stress response mediated in part by fungal MAPK cascades. In this review, we make use of the genomic data available following completion of whole-genome sequencing projects to analyze the structure of MAPK protein families in 24 fungal taxa, including both plant pathogens and mycorrhizal symbionts. Based on conserved patterns of sequence diversification, we also propose the adoption of a unified fungal MAPK nomenclature derived from that established for the model species Saccharomyces cerevisiae. Finally, we summarize current knowledge of the functions of MAPK cascades in phytopathogenic fungi and highlight the central role played by MAPK signaling during the molecular dialogue between plants and invading fungal pathogens.

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Section: Mapks From Phytopathogenic Fungimentioning

confidence: 95%

Mitogen-Activated Protein Kinase Signaling in Plant-Interacting Fungi: Distinct Messages from Conserved Messengers

et al. 2012

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“…The ends of chromosomes were identified by the telomere repeat motif (TTAGGG)n. Thirteen telomeric sequences were placed at the ends of scaffolds, of which six could be placed at the ends of chromosomes, whereas the remainder were associated with unanchored scaffolds (Supplementary Table S2). Genome coverage was estimated by aligning 28,682 M. grisea expressed sequence tags (ESTs), representing genes expressed during a range of developmental stages and environmental conditions 10,11 . Approximately 94% of the ESTs were aligned to the genome assembly, despite many of these ESTs being from different strains.…”

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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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“…They are involved in surface sensing, signaling, melanin/sugar/lipids metabolism, secretion, and membrane remodeling (42). M. grisea genes expressed in infected tissues (28) and appressoria (3,11,16,23,30,41) were also identified using genomic tools (expressed sequence tags, arrays). Up to now, only a few of these genes are specifically expressed in appressoria or during infection.…”

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Expression of Magnaporthe grisea Avirulence Gene ACE1 Is Connected to the Initiation of Appressorium-Mediated Penetration

et al. 2007

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Magnaporthe grisea is responsible for a devastating fungal disease of rice called blast. Current control of this disease relies on resistant rice cultivars that recognize M. grisea signals corresponding to specific secreted proteins encoded by avirulence genes. The M. grisea ACE1 avirulence gene differs from others, since it controls the biosynthesis of a secondary metabolite likely recognized by rice cultivars carrying the Pi33 resistance gene. Using a transcriptional fusion between ACE1 promoter and eGFP, we showed that ACE1 is only expressed in appressoria during fungal penetration into rice and barley leaves, onion skin, and cellophane membranes. ACE1 is almost not expressed in appressoria differentiated on Teflon and Mylar artificial membranes. ACE1 expression is not induced by cellophane and plant cell wall components, demonstrating that it does not require typical host plant compounds. Cyclic AMP (cAMP) signaling mutants ⌬cpkA and ⌬mac1 sum1-99 and tetraspanin mutant ⌬pls1::hph differentiate melanized appressoria with normal turgor but are unable to penetrate host plant leaves. ACE1 is normally expressed in these mutants, suggesting that it does not require cAMP signaling or a successful penetration event. ACE1 is not expressed in appressoria of the buf1::hph mutant defective for melanin biosynthesis and appressorial turgor. The addition of hyperosmotic solutes to buf1::hph appressoria restores appressorial development and ACE1 expression. Treatments of young wild-type appressoria with actin and tubulin inhibitors reduce both fungal penetration and ACE1 expression. These experiments suggest that ACE1 appressorium-specific expression does not depend on host plant signals but is connected to the onset of appressorium-mediated penetration.Magnaporthe grisea species complex attacks a wide range of grasses, including wheat, barley, and rice (10,26), and is a model organism for the study of plant fungal interactions (11, 42). The M. grisea infection cycle is characteristic of grass leaf spot diseases. After spore attachment and germination, the fungus differentiates an appressorium through the perception of physical and chemical surface parameters (hydrophobicity, hardness, and cuticle monomers) (21, 42). This differentiation is the result of a complex morphogenetic process that involves cyclic AMP (cAMP), mitogen-activated protein kinases, and calcium signaling pathways (7,45,50). Early stages of appressorium development are associated with the deposition of a melanin layer between the cell wall and plasma membrane (21), migration of lipid bodies from spore to appressorium, mobilization of glycogen, and the formation of a septum sealing the appressorium (5, 43). Maturation of the appressorium is characterized by the degradation of lipid bodies and glycogen (43) and the generation of a high turgor (22). Finally, a reorganization of the cytoskeleton is induced at the point of emergence of the penetration peg that penetrates the host cuticle and cell wall (5,35). Inside the plant, M. grisea differentiates bulbous...

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Gene Discovery and Gene Expression in the Rice Blast Fungus, Magnaporthe grisea: Analysis of Expressed Sequence Tags

Cited by 87 publications

References 40 publications

Mitogen-Activated Protein Kinase Signaling in Plant-Interacting Fungi: Distinct Messages from Conserved Messengers

Mitogen-Activated Protein Kinase Signaling in Plant-Interacting Fungi: Distinct Messages from Conserved Messengers

The genome sequence of the rice blast fungus Magnaporthe grisea

Expression of Magnaporthe grisea Avirulence Gene ACE1 Is Connected to the Initiation of Appressorium-Mediated Penetration

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