Chitin induced PTI in Wheat
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Rescooped by William Kay from Trends in MPMI
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MPMI: Effectors as tools in disease resistance breeding against biotrophic, hemi-biotrophic and necrotrophic plant pathogens (2014)

MPMI: Effectors as tools in disease resistance breeding against biotrophic, hemi-biotrophic and necrotrophic plant pathogens (2014) | Chitin induced PTI in Wheat | Scoop.it

One of most important challenges in plant breeding is improving resistance to the plethora of pathogens that threaten our crops. The ever growing world population, changing pathogen populations and fungicide resistance issues have increased the urgency of this task. In addition to a vital inflow of novel resistance sources into breeding programmes, the functional characterisation and deployment of resistance also needs improvement. Plant breeders therefore need to adopt new strategies and techniques. In modern resistance breeding, effectors are emerging as tools to accelerate and improve the identification, functional characterisation and deployment of R genes. Since genome-wide catalogues of effectors have become available for various pathogens, including biotrophs as well as necrotrophs, effector-assisted breeding has been shown to be successful for various crops. “Effectoromics” has contributed to classical resistance breeding as well as for GM approaches. Here we present an overview of how effector-assisted breeding and deployment is being exploited for various pathosystems.


Via Kamoun Lab @ TSL, CP
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Rescooped by William Kay from Trends in MPMI
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Gene silencing and gene expression in phytopathogenic fungi using a plant virus vector

RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including phytopathogenic fungi. In such fungi, RNAi has been induced by expressing hairpin RNAs delivered through plasmids, sequences integrated in fungal or plant genomes, or by RNAi generated in planta by a plant virus infection. All these approaches have some drawbacks ranging from instability of hairpin constructs in fungal cells to difficulties in preparing and handling transgenic plants to silence homologous sequences in fungi grown on these plants. Here we show that RNAi can be expressed in the phytopathogenic fungus Colletotrichum acutatum (strain C71) by virus-induced gene silencing (VIGS) without a plant intermediate, but by using the direct infection of a recombinant virus vector based on the plant virus, tobacco mosaic virus (TMV). We provide evidence that a wild-type isolate of TMV is able to enter C71 cells grown in liquid medium, replicate, and persist therein. With a similar approach, a recombinant TMV vector carrying a gene for the ectopic expression of the green fluorescent protein (GFP) induced the stable silencing of the GFP in the C. acutatum transformant line 10 expressing GFP derived from C71. The TMV-based vector also enabled C. acutatum to transiently express exogenous GFP up to six subcultures and for at least 2 mo after infection, without the need to develop transformation technology. With these characteristics, we anticipate this approach will find wider application as a tool in functional genomics of filamentous fungi.


Via Jennifer Mach, CP
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Rescooped by William Kay from Trends in MPMI
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Plant PRRs and the Activation of Innate Immune Signaling: Molecular Cell

Plant PRRs and the Activation of Innate Immune Signaling: Molecular Cell | Chitin induced PTI in Wheat | Scoop.it

Despite being sessile organisms constantly exposed to potential pathogens and pests, plants are surprisingly resilient to infections. Plants can detect invaders via the recognition of pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors (PRRs). Plant PRRs are surface-localized receptor-like kinases, which comprise a ligand-binding ectodomain and an intracellular kinase domain, or receptor-like proteins, which do not exhibit any known intracellular signaling domain. In this review, we summarize recent discoveries that shed light on the molecular mechanisms underlying ligand perception and subsequent activation of plant PRRs. Notably, plant PRRs appear as central components of multiprotein complexes at the plasma membrane that contain additional transmembrane and cytosolic kinases required for the initiation and specificity of immune signaling. PRR complexes are under tight control by protein phosphatases, E3 ligases, and other regulatory proteins, illustrating the exquisite and complex regulation of these molecular machines whose proper activation underlines a crucial layer of plant immunity.


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Rescooped by William Kay from Plant pathogens and pests
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Mycosphaerella graminicola LysM Effector-Mediated Stealth Pathogenesis Subverts Recognition Through Both CERK1 and CEBiP Homologues in Wheat

Mycosphaerella graminicola LysM Effector-Mediated Stealth Pathogenesis Subverts Recognition Through Both CERK1 and CEBiP Homologues in Wheat | Chitin induced PTI in Wheat | Scoop.it

Fungal cell-wall chitin is a well-recognized pathogen-associated molecular pattern. Recognition of chitin in plants by pattern recognition receptors activates pathogen-triggered immunity (PTI). In Arabidopsis, this process is mediated by a plasma membrane receptor kinase, CERK1, whereas in rice, a receptor-like protein, CEBiP, in addition to CERK1 is required. Secreted chitin-binding lysin motif (LysM) containing fungal effector proteins, such as Ecp6 from the biotrophic fungus Cladosporium fulvum, have been reported to interfere with PTI. Here, we identified wheat homologues of CERK1 and CEBiP and investigated their role in the interaction with the nonbiotrophic pathogen of wheat Mycosphaerella graminicola (synonym Zymoseptoria tritici). We show that silencing of either CERK1 or CEBiP in wheat, using Barley stripe mosaic virus–mediated virus-induced gene silencing, is sufficient in allowing leaf colonization by the normally nonpathogenic M. graminicola Mg3LysM (homologue of Ecp6) deletion mutant, while the Mg1LysM deletion mutant was fully pathogenic toward both silenced and wild-type wheat leaves. These data indicate that Mg3LysM is important for fungal evasion of PTI in wheat leaf tissue and that both CERK1 and CEBiP are required for activation of chitin-induced defenses, a feature conserved between rice and wheat, and perhaps, also in other cereal species.


Via Christophe Jacquet
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Rescooped by William Kay from WHEAT
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Australia: Wheat faces new threat - fungicide-resistant Septoria tritici blotch

Australia: Wheat faces new threat - fungicide-resistant Septoria tritici blotch | Chitin induced PTI in Wheat | Scoop.it

Researchers have discovered the first record of a wheat pathogen developing fungicide resistance in Australia.

Fungicide-resistant Septoria tritici blotch (STB) has been identified in a number of Australian wheat crops by researchers at the Department of Primary Industries (DPI) Wagga Wagga Research Institute and Charles Sturt University (CSU).


Via CIMMYT, Int.
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PLOS Biology: Unsolved Mystery - How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells? (2014)

PLOS Biology: Unsolved Mystery - How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells? (2014) | Chitin induced PTI in Wheat | Scoop.it

Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens.


Via Kamoun Lab @ TSL, CP
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Current Opinion in Plant Biology-Inside plant: biotrophic strategies to modulate host immunity and metabolism

Current Opinion in Plant Biology-Inside plant: biotrophic strategies to modulate host immunity and metabolism | Chitin induced PTI in Wheat | Scoop.it

Filamentous plant pathogens that establish biotrophic interactions need to avoid plant immune responses. Recent findings from different pathosystems suggest that sufficient suppression of host immunity is based on the modulation of a rather limited number of host targets. Microbial strategies to target host physiology dependent on the duration of biotrophy, the style of host tissue colonization and the degree of interference with plant development. In this article, we present current concepts in biotrophic virulence strategies and discuss mechanisms of pathogen adaptation and effector specialization.


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Rescooped by William Kay from Plant immunity and legume symbiosis
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Chitin-induced activation of immune signaling by the rice receptor CEBiP relies on a unique sandwich-type dimerization

Chitin-induced activation of immune signaling by the rice receptor CEBiP relies on a unique sandwich-type dimerization | Chitin induced PTI in Wheat | Scoop.it

Perception of microbe-associated molecular patterns (MAMPs) through pattern recognition receptors (PRRs) triggers various defense responses in plants. This MAMP-triggered immunity plays a major role in the plant resistance against various pathogens. To clarify the molecular basis of the specific recognition of chitin oligosaccharides by the rice PRR, CEBiP (chitin-elicitor binding protein), as well as the formation and activation of the receptor complex, biochemical, NMR spectroscopic, and computational studies were performed. Deletion and domain-swapping experiments showed that the central lysine motif in the ectodomain of CEBiP is essential for the binding of chitin oligosaccharides. Epitope mapping by NMR spectroscopy indicated the preferential binding of longer-chain chitin oligosaccharides, such as heptamer-octamer, to CEBiP, and also the importance of N-acetyl groups for the binding. Molecular modeling/docking studies clarified the molecular interaction between CEBiP and chitin oligosaccharides and indicated the importance of Ile122 in the central lysine motif region for ligand binding, a notion supported by site-directed mutagenesis. Based on these results, it was indicated that two CEBiP molecules simultaneously bind to one chitin oligosaccharide from the opposite side, resulting in the dimerization of CEBiP. The model was further supported by the observations that the addition of (GlcNAc)8 induced dimerization of the ectodomain of CEBiP in vitro, and the dimerization and (GlcNAc)8-induced reactive oxygen generation were also inhibited by a unique oligosaccharide, (GlcNβ1,4GlcNAc)4, which is supposed to have N-acetyl groups only on one side of the molecule. Based on these observations, we proposed a hypothetical model for the ligand-induced activation of a receptor complex, involving both CEBiP and Oryza sativa chitin-elicitor receptor kinase-1.


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Christophe Jacquet's curator insight, January 13, 2014 2:48 AM

Significance

Chitin perception by plant receptors triggers various defense responses important for plant immunity. We show the molecular basis of chitin recognition by the rice receptor, CEBiP (chitin-elicitor binding protein), and following receptor dimerization based on the results of biochemical studies, epitope mapping by saturation transfer difference NMR spectroscopy and molecular modeling/docking studies. These results clearly indicated that two CEBiP molecules simultaneously bind to one N-acetylchitoheptaose/octaose from the opposite side, through a binding site in the central lysin motif region, resulting in the dimerization of CEBiP. Based on these observations, we proposed a hypothetical model for the ligand-induced activation of a receptor complex, involving CEBiP and Oryza sativa chitin-elicitor receptor kinase 1 (OsCERK1).

Rescooped by William Kay from Plants and Microbes
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MPMI: Mycosphaerella graminicola LysM effector-mediated stealth pathogenesis subverts recognition through both CERK1 and CEBiP homologues in wheat (2013)

MPMI: Mycosphaerella graminicola LysM effector-mediated stealth pathogenesis subverts recognition through both CERK1 and CEBiP homologues in wheat (2013) | Chitin induced PTI in Wheat | Scoop.it

Fungal cell wall chitin is a well-recognized pathogen-associated molecular pattern. Recognition of chitin in plants by pattern recognition receptors activates pathogen triggered immunity (PTI). In Arabidopsis this process is mediated by a plasma membrane receptor kinase CERK1, whereas in rice a receptor-like protein CEBiP in addition to CERK1 is required. Secreted chitin-binding lysin motif (LysM) containing fungal effector proteins such as Ecp6 from the biotrophic fungusCladosporium fulvum have been reported to interfere with PTI. Here we identified wheat homologues of CERK1 and CEBiP and investigated their role in the interaction with the non-biotrophic pathogen of wheatMycosphaerella graminicola (synonym Zymoseptoria tritici). We show that silencing of either CERK1 or CEBiP in wheat using Barley stripe mosaic virus-mediated Virus-induced gene silencing (BSMV-VIGS) is sufficient in allowing leaf colonization by the normally nonpathogenic M. graminicola Mg3LysM (homologue of Ecp6) deletion mutant, while theMg1LysM deletion mutant was fully pathogenic toward both silenced and wild type wheat leaves. These data indicate that Mg3LysM is important for fungal evasion of PTI in wheat leaf tissue and that both CERK1 and CEBiP are required for activation of chitin-induced defenses, a feature conserved between rice and wheat, and also perhaps in other cereal species.


Via Kamoun Lab @ TSL
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Stephen Bolus's curator insight, February 10, 2014 1:52 AM

I want to do VIGS on wheat!

Rescooped by William Kay from WHEAT
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US: Online tool can determine if fungicides are needed for wheat

US: Online tool can determine if fungicides are needed for wheat | Chitin induced PTI in Wheat | Scoop.it
With Ohio wheat nearing the critical flowering growth stage, it’s important for growers to use a regional online assessment tool to determine their risk for Fusarium head blight development, according to a wheat expert from Ohio State University’s College of Food, Agricultural, and Environmental Sciences.

Via CIMMYT, Int.
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