The molecular biology of appressorium turgor generation by the rice blast fungus <i>Magnaporthe grisea</i>

Wang, Z.-Y.; Jenkinson, Joanna M.; Holcombe, Lucy J.; Soanes, Darren M.; Veneault‐Fourrey, Claire; Bhambra, G.K.; Talbot, Nicholas J.

doi:10.1042/bst0330384

Cited by 93 publications

(70 citation statements)

References 28 publications

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“…36 However, in the study of Magnaporthe gasea, trehalose synthesis is required for virulence and it is possible that either trehalose accumulates as an accessory-compatible solute in appressoria or the sugar plays a role in the regulation of appressorium turgor generation. 37 Relative to mycelia, metabolites related to oxidative stress, such as carnitine, acetylcarnitine, oxylipins, ergothioneine, trehalose, mannitol, etc., are either not significantly changed or even reduced in conidia, which indicated that the oxidative stress is generated in the processes of transcription and translation. There is no significant oxidative stress reaction when the aaIT gene is quiescent in conidia.…”

Section: Resultsmentioning

confidence: 99%

Metabolic Effect of an Exogenous Gene on Transgenic Beauveria bassiana Using Liquid Chromatography–Mass Spectrometry-Based Metabolomics

Luo

Zhou

et al. 2013

J. Agric. Food Chem.

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Metabolic effect of an exogenous gene on transgenic beauveria bassiana using liquid chromatography-mass spectrometry-based metabolomics (with F. Luo et al.) ABSTRACT: Genetic modification of Beauveria bassiana with the scorpion neurotoxin aaIT gene can distinctly increase its insecticidal activity, whereas the effect of this exogenous gene on the metabolism of B. bassiana is unknown until now. Thus, we investigate the global metabolic profiling of mycelia and conidia of transgenic and wild-type B. bassiana by liquid chromatography−mass spectrometry (LC−MS). Principal component analysis (PCA) and orthogonal projection to latent structure discriminant analysis (OPLS-DA) reveal clear discrimination of wild-type mycelia and conidia from transgenic mycelia and conidia. The decrease of glycerophospholipids, carnitine, and fatty acids and the increase of oxylipins, glyoxylate, pyruvic acid, acetylcarnitine, fumarate, ergothioneine, and trehalose in transgenic mycelia indicate the enhanced oxidative reactions. In contrast, most metabolites related to oxidative stress are not altered significantly in conidia, which implies that there will be no significant oxidative stress reaction when the aaIT gene is quiescent in cells.

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Section: Resultsmentioning

confidence: 99%

Metabolic Effect of an Exogenous Gene on Transgenic Beauveria bassiana Using Liquid Chromatography–Mass Spectrometry-Based Metabolomics

Luo

Zhou

et al. 2013

J. Agric. Food Chem.

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“…One possible explanation is that the slender conidia of the Mgrho3 mutant may have less carbon storage than normal pyriform conidia. In M. grisea, carbon storage, such as in glycogen and lipid bodies, plays an important role in appressorium turgor generation (12,39). Therefore, it is likely that appressoria formed by the Mgrho3 mutants are defective in penetration because of the reduced turgor pressure.…”

Section: Discussionmentioning

confidence: 99%

A Rho3 Homolog Is Essential for Appressorium Development and Pathogenicity of Magnaporthe grisea

et al. 2007

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The small GTPase Rho3 is conserved in fungi and plays a key role in the control of cell polarity and exocytosis in yeast. In this report, we show that a Rho3 homolog, MgRho3, is dispensable for polarized hyphal growth in the rice blast fungus Magnaporthe grisea. However, MgRho3 is required for plant infection. Appressoria formed by the Mgrho3 deletion mutants are morphologically abnormal and defective in plant penetration. Conidia of the Mgrho3 deletion mutants are narrower than those of the wild-type strain and delayed in germination. Transformants expressing a dominant negative Mgrho3 allele exhibit similar phenotypes as the Mgrho3 deletion mutant, while transformants expressing a constitutively active allele of MgRho3 can produce normal conidia but remain defective in appressorium formation and plant infection. In contrast, overexpression of wild-type MgRho3 increases the infectivity of M. grisea. Our results reveal a new role for the conserved Rho3 as a critical regulator of developmental processes and pathogenicity of M. grisea.Magnaporthe grisea is an ascomycete pathogen of important cereal crops, such as rice, barley, and wheat. It causes rice blast, one of the most severe fungal diseases of rice throughout the world (33, 35). The fungus infects rice plants in a sophisticated manner, like many other foliar pathogens. Germ tubes produced from conidia differentiate into specialized infection structures called appressoria and then use the enormous turgor pressure generated in appressoria for plant penetration (8). Mature appressoria develop thin penetration pegs to physically pierce the host surface and enter plant epidermal cells. At early stages, the penetration peg contains high concentrations of actin filaments (3) and recruits the rice cell membrane to form the extrainvasive hyphal membrane, while infection hyphal growth and its co-opt plasmodesmata for cell-to-cell movement (18). It has been hypothesized that actin and cytoskeleton elements may be involved in the reestablishment of polarized growth by determining the penetration site and in stabilizing the tip of the penetration peg (15). After penetration, the peg differentiates into infectious hyphae that grow inter-and intracellularly and result in development of blast lesions.Signal transduction pathways that regulate infection-related morphogenesis have been extensively studied in M. grisea during the past few years (34, 41). In general, cyclic AMP (cAMP) signaling is involved in surface recognition and initiation of appressorium formation (1,20,22,44). However, appressorium formation is regulated by the Pmk1 mitogen-activated protein kinase pathway (25,42,46). The pmk1 deletion mutant fails to form appressoria and is nonpathogenic. One putative transcription factor regulated by PMK1 is MST12, which is homologous to Saccharomyces cerevisiae Ste12 and essential for pathogenesis (27). The mst12 deletion mutant forms melanized appressoria that have normal appressorium turgor but fail to develop penetration pegs, probably due to cytoskeleton defects i...

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“…While this reduction in epiphyllous growth was unexpected, it is not without explanation. The apparent inability of the DsakA mutant to penetrate the host cuticle is likely due to an inability to establish sufficient turgor pressure, or alternatively to produce degradative enzymes, for penetration (Wang et al, 2005;Noguchi et al, 2007). This would limit epiphyllous growth to those few hyphae that encounter and grow out of host stomatal openings, analogous to how some phytopathogenic fungi enter host tissues (Willmer and Fricker, 1996).…”

Section: Discussionmentioning

confidence: 99%

Disruption of Signaling in a Fungal-Grass Symbiosis Leads to Pathogenesis

et al. 2010

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Symbiotic associations between plants and fungi are a dominant feature of many terrestrial ecosystems, yet relatively little is known about the signaling, and associated transcriptome profiles, that define the symbiotic metabolic state. Using the Epichloë festucae-perennial ryegrass (Lolium perenne) association as a model symbiotic experimental system, we show an essential role for the fungal stress-activated mitogen-activated protein kinase (sakA) in the establishment and maintenance of this mutualistic interaction. Deletion of sakA switches the fungal interaction with the host from mutualistic to pathogenic. Infected plants exhibit loss of apical dominance, premature senescence, and dramatic changes in development, including the formation of bulb-like structures at the base of tillers that lack anthocyanin pigmentation. A comparison of the transcriptome of wild-type and sakA associations using high-throughput mRNA sequencing reveals dramatic changes in fungal gene expression consistent with the transition from restricted to proliferative growth, including a down-regulation of several clusters of secondary metabolite genes and up-regulation of a large set of genes that encode hydrolytic enzymes and transporters. Analysis of the plant transcriptome reveals up-regulation of host genes involved in pathogen defense and transposon activation as well as dramatic changes in anthocyanin and hormone biosynthetic/responsive gene expression. These results highlight the fine balance between mutualism and antagonism in a plant-fungal interaction and the power of deep mRNA sequencing to identify candidate sets of genes underlying the symbiosis.

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The molecular biology of appressorium turgor generation by the rice blast fungus Magnaporthe grisea

Cited by 93 publications

References 28 publications

Metabolic Effect of an Exogenous Gene on Transgenic Beauveria bassiana Using Liquid Chromatography–Mass Spectrometry-Based Metabolomics

Metabolic Effect of an Exogenous Gene on Transgenic Beauveria bassiana Using Liquid Chromatography–Mass Spectrometry-Based Metabolomics

A Rho3 Homolog Is Essential for Appressorium Development and Pathogenicity of Magnaporthe grisea

Disruption of Signaling in a Fungal-Grass Symbiosis Leads to Pathogenesis

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