Fusarium graminearum on plant cell wall: No fewer than 30 xylanase genes transcribed

Hatsch, Didier; Phalip, Vincent; Petkovski, Elizabet; Jeltsch, Jean‐Marc

doi:10.1016/j.bbrc.2006.04.171

Cited by 42 publications

(29 citation statements)

References 26 publications

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“…Cytological studies have provided indirect evidence that G. zeae produces cellulose, xylanase, and pectinase during plant penetration and colonization (62). In addition, G. zeae grown on the plant cell wall in vitro expresses more than 40 putative genes related to polysaccharide degradation or carbohydrate catabolism (43), and at least 30 putative xylanases are expressed in the plant cell wall medium (22). ⌬GzSNF1 mutants had reduced virulence capabilities and expression of cell-wall-degrading enzymes, as has been found in similar mutants in other plant pathogenic fungi (42,55).…”

Section: Discussionmentioning

confidence: 77%

“…⌬FoSNF1 mutants also use pectin efficiently, whereas ⌬CcSNF1 mutants could not use either pectin or xylan as a carbon source (42,55). Xylan and pectin are major components of the plant cell wall (22,43,62). The differences in the carbon source utilization pattern among the different fungal species could result from differences in the activity of cell-walldegrading enzymes depolymerized by genes regulated by SNF1.…”

Section: Discussionmentioning

confidence: 99%

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GzSNF1Is Required for Normal Sexual and Asexual Development in the AscomyceteGibberella zeae

Lee

et al. 2009

Eukaryot Cell

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The sucrose nonfermenting 1 (SNF1) protein kinase of yeast plays a central role in the transcription of glucose-repressible genes in response to glucose starvation. In this study, we deleted an ortholog of SNF1 from Gibberella zeae to characterize its functions by using a gene replacement strategy. The mycelial growth of deletion mutants (⌬GzSNF1) was reduced by 21 to 74% on diverse carbon sources. The virulence of ⌬GzSNF1 mutants on barley decreased, and the expression of genes encoding cell-wall-degrading enzymes was reduced. The most distinct phenotypic changes were in sexual and asexual development. ⌬GzSNF1 mutants produced 30% fewer perithecia, which matured more slowly, and asci that contained one to eight abnormally shaped ascospores. Mutants in which only the GzSNF1 catalytic domain was deleted had the same phenotype changes as the ⌬GzSNF1 strains, but the phenotype was less extreme in the mutants with the regulatory domain deleted. In outcrosses between the ⌬GzSNF1 mutants, each perithecium contained ϳ70% of the abnormal ascospores, and ϳ50% of the asci showed unexpected segregation patterns in a single locus tested. The asexual spores of the ⌬GzSNF1 mutants were shorter and had fewer septa than those of the wild-type strain. The germination and nucleation of both ascospores and conidia were delayed in ⌬GzSNF1 mutants in comparison with those of the wild-type strain. GzSNF1 expression and localization depended on the developmental stage of the fungus. These results suggest that GzSNF1 is critical for normal sexual and asexual development in addition to virulence and the utilization of alternative carbon sources.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

GzSNF1Is Required for Normal Sexual and Asexual Development in the AscomyceteGibberella zeae

Lee

et al. 2009

Eukaryot Cell

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“…XynBc1, a GH11 xylanase cloned from Botrytis cinerea, was inhibited by TAXI-I but not by TAXI-II, suggesting that these inhibitors can be specific and have perhaps coevolved with their targets [12 ]. However, these interactions are just the tip of the iceberg, as F. graminearum has over 30 different xylanase genes that are induced during infection [13]. The crystal structure of TAXI has a striking structural homology with pepsin-like aspartic proteases but it lacks the required catalytic triad, suggesting that this inhibitor evolved from a pepsin-like aspartic protease ancestor [14].…”

Section: Wheat Inhibitor Taxi Targets Pathogen Gh11 Xylanasesmentioning

confidence: 99%

“…TAXI can only inhibit GH11 xylanases, which are b-jelly roll proteins that fold like a hand with the catalytic glutamine residues in the 'palm', covered by a 'thumb' [10]. TAXI-I Extracellular enzymeinhibitor interactions Misas-Villamil and van der Hoorn 381 However, these interactions are just the tip of the iceberg, as F. graminearum has over 30 different xylanase genes that are induced during infection [13]. The crystal structure of TAXI has a striking structural homology with pepsin-like aspartic proteases but it lacks the required catalytic triad, suggesting that this inhibitor evolved from a pepsin-like aspartic protease ancestor [14].…”

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confidence: 99%

Enzyme–inhibitor interactions at the plant–pathogen interface

Misas-Villamil

Hoorn

2008

Current Opinion in Plant Biology

115

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The plant apoplast during plant-pathogen interactions is an ancient battleground that holds an intriguing range of attacking enzymes and counteracting inhibitors. Examples are pathogen xylanases and polygalacturonases that are inhibited by plant proteins like TAXI, XIP, and PGIP; and plant glucanases and proteases, which are targeted by pathogen proteins such as GIP1, EPI1, EPIC2B, and AVR2. These seven well-characterized inhibitors have different modes of action and many probably evolved from inactive enzymes themselves. Detailed studies of the structures, sequence variation, and mutated proteins uncovered molecular struggles between these enzymes and their inhibitors, resulting in positive selection for variant residues at the contact surface, where single residues determine the outcome of the interaction. Introduction Extracellular plant-pathogen interactions probably existed long before the evolution of pathogen effector translocation systems and plant resistance (R) genes. The molecular basis of these interactions is mostly undiscovered but some have been investigated in detail and reveal intriguing mechanisms. Here we will highlight major recent findings of extracellular enzyme-inhibitor interactions at the plant-pathogen interface.Although extracellular plant-pathogen interactions are complex, they can be simplified by assuming that they evolved in several stages (Figure 1). First, micro-organisms became pathogens by attacking plants using cell-wall-degrading enzymes and other hydrolases ( Figure 1A). In response to this attack, plants secrete inhibitors that suppress these hydrolases ( Figure 1B). Initially, these inhibitors were probably constitutively produced, but upon evolution of pathogen recognition systems the production and secretion of these proteins became inducible, becoming part of the arsenal of pathogenesis-related (PR) proteins. Besides suppression of pathogen attack, counter attack mechanisms also evolved in plants through the induced secretion of hydrolytic enzymes ( Figure 1C). Examples are the well-studied PR proteins including endo-b-1,3-glucanases (PR-2), chitinases (PR-3), and proteases (PR-7) [1 ]. Pathogens, in turn, responded to this counter attack by producing inhibitors that suppress these enzymes ( Figure 1D). The fifth and latest step was a sophisticated refinement of the pathogen recognition system by the evolution of R genes that recognize the manipulation of plant targets by pathogens, inducing a severe defense response that includes cell death ( Figure 1E). Aspects of this simplified model are consistent with the 'zigzag' model for the plant immune system, which explains the suppression of basal defense responses by pathogen effector proteins, followed by the evolution of efficient effector recognition by R proteins [2].Antagonistic interactions between organisms at the molecular level result in enzymes that evade inhibition, and inhibitors that adapt to these new enzymes. These 'molecular struggles' result in positive selection for variation of residues at the interactio...

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“…By analogy with the enzymes already characterized, it means that slightly different specificities are likely to be discovered and could be essential to complete plant cell wall degradation. Furthermore, quantitative studies performed on Fusarium hemicellulases demonstrate that on hop cell wall, the expression level of the 30 putative enzymes varies greatly from 1 (the less abundant) to 1500 (Hatsch et al, 2006). When another biomass is used for growth, the pattern of secreted enzymes is different, clearly indicating that there is no "general response" to the presence of plant material but specific responses to a given biomass.…”

Section: Enzymatic Measurementsmentioning

confidence: 99%

Competing Plant Cell Wall Digestion Recalcitrance by Using Fungal Substrate – Adapted Enzyme Cocktails

Phalip¹,

Debeire²,

Jeltsch³

2012

Bioethanol

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Fusarium graminearum on plant cell wall: No fewer than 30 xylanase genes transcribed

Cited by 42 publications

References 26 publications

GzSNF1Is Required for Normal Sexual and Asexual Development in the AscomyceteGibberella zeae

GzSNF1Is Required for Normal Sexual and Asexual Development in the AscomyceteGibberella zeae

Enzyme–inhibitor interactions at the plant–pathogen interface

Competing Plant Cell Wall Digestion Recalcitrance by Using Fungal Substrate – Adapted Enzyme Cocktails

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