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Rice OsPAD4 functions differently from Arabidopsis AtPAD4 in host-pathogen interactions

Rice OsPAD4 functions differently from Arabidopsis AtPAD4 in host-pathogen interactions | Biotic | Scoop.it

The extensively studied Arabidopsis phytoalexin deficient 4 (AtPAD4) gene plays an important role in Arabidopsis disease resistance. However, the function of its sequence ortholog in rice is unknown. Here, we show that rice OsPAD4 appears not to be the functional ortholog of AtPAD4 in host–pathogen interactions, and that the former (OsPAD4) encodes a plasma membrane protein but the latter (AtPAD4) encodes a cytoplasmic and nuclear protein. Suppression of OsPAD4 by RNA interference (RNAi) increased rice susceptibility to biotrophic pathogen Xanthomonas oryzae pv. oryzae (Xoo), which causes bacteria blight disease in local tissue. OsPAD4–RNAi plants also show compromised wound-induced systemic resistance to Xoo. The increased susceptibility to Xoo was associated with reduced accumulation of jasmonic acid (JA) and phytoalexin momilactone A (MOA). Exogenous application of JA complemented the phenotype of OsPAD4–RNAi plants in response to Xoo. The following results suggest that OsPAD4 functions differently than AtPAD4 in response to pathogen infection. First, OsPAD4 plays an important role in wound-induced systemic resistance, whereas AtPAD4 mediates systemic acquired resistance. Second, OsPAD4-involved defense signaling against Xoo is JA-dependent, but AtPAD4-involved defense signaling against biotrophic pathogens is salicylic acid–dependent. Finally, OsPAD4 is required for the accumulation of terpenoid-type phytoalexin MOA in rice–bacterium interactions, but AtPAD4-mediated resistance is associated with the accumulation of indole-type phytoalexin camalexin.

 

 


Via Christophe Jacquet, Elsa Ballini
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Plasma membrane localization is essential for OsPti1a-mediated negative regulation of immune signaling in rice

Plasma membrane localization is essential for OsPti1a-mediated negative regulation of immune signaling in rice | Biotic | Scoop.it

OsPti1a, an ortholog of tomato SlPti1, functions as a negative regulator of innate immunity in rice (Oryza sativa L.). In ospti1a mutants, the activation of immune responses including HR-like cell death is caused by the loss of OsPti1a protein; however, it is as yet unclear how OsPti1a suppresses immune responses. Here, we report that OsPti1a localizes to detergent-resistant membrane (DRM) fractions of the plasma membrane through lipid modification of the protein’s N-terminus, which is highly conserved among Pti1 orthologs in several plant species. Importantly, mis-localization of OsPti1a after deletion of its N-terminus reduced its ability to complement the mutant phenotypes including HR-like cell death. Further, complex formation of OsPti1a depends on its N terminus-mediated membrane localization. LC-MS/MS analysis of OsPti1a complex-interacting proteins identified several defense-related proteins. Collectively, these findings indicate that appropriate complex formation by OsPti1a at the plasma membrane is required for negative regulation of plant immune responses in rice.


Via Christophe Jacquet, Elsa Ballini
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Nature Reviews Immunology: Effector-triggered versus pattern-triggered immunity: how animals sense pathogens (2013)

Nature Reviews Immunology: Effector-triggered versus pattern-triggered immunity: how animals sense pathogens (2013) | Biotic | Scoop.it

http://www.nature.com/nri/journal/vaop/ncurrent/full/nri3398.html

 

A fundamental question regarding any immune system is how it can discriminate between pathogens and non-pathogens. Here, we discuss how this discrimination can be mediated by a surveillance system distinct from pattern-recognition receptors that recognize conserved microbial patterns. It can be based instead on the ability of the host to sense perturbations in host cells induced by bacterial toxins or 'effectors' that are encoded by pathogenic microorganisms. Such 'effector-triggered immunity' was previously demonstrated mainly in plants, but recent data confirm that animals can also use this strategy.


Via Kamoun Lab @ TSL, Ricardo Oliva
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Jennifer Mach's comment, February 19, 2013 8:36 AM
"...previously demonstrated mainly in plants, but recent data confirm that animals can also use this strategy." This sentence should be read by all granting agencies.
Freddy Monteiro's comment, February 19, 2013 9:47 AM
with all due respect, this was the kind of information and approach I was expecting at the 2012 IS-MPMI Congress opening lecture.
Kamoun Lab @ TSL's comment, February 20, 2013 10:44 PM
Freddy, yes you have a point. Sadly, our animal immunity colleagues seem oblivious to the plant literature. I think the authors of this review have earned themselves many invitations on the plant biology lecture circuit.
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Plant Cell: Plant Immune Responses Against Viruses: How Does a Virus Cause Disease?

Plant Cell: Plant Immune Responses Against Viruses: How Does a Virus Cause Disease? | Biotic | Scoop.it

New review article in Plant Cell.

"Recently, significant progress has been made in understanding RNA silencing and how viruses counter this apparently ubiquitous antiviral defense. In addition, plants also induce hypersensitive and systemic acquired resistance responses, which together limit the virus to infected cells and impart resistance to the noninfected tissues."


Via Mary Williams, Ricardo Oliva
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Andres Zurita's curator insight, May 29, 2013 8:28 AM

Open Access pdf

María Serrano's curator insight, June 24, 2014 12:30 PM
Respuesta inmune de las plantas frente a los virus.
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Genome Biology: Interactions of beneficial and detrimental root-colonizing filamentous microbes with plant hosts (2013)

Genome Biology: Interactions of beneficial and detrimental root-colonizing filamentous microbes with plant hosts (2013) | Biotic | Scoop.it

Understanding commonalities and differences of how symbiotic and parasitic microbes interact with plants will improve advantageous interactions and allow pathogen control strategies in crops. Recently established systems enable studies of root pathogenic and symbiotic interactions in the same plant species.


Via Kamoun Lab @ TSL, Ricardo Oliva
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João Miguel Correia Teixeira's comment, July 4, 2013 6:14 AM
Very nice initiative! You continue to surprise me the same way you did the first day we met ;-)
Ronaldo Dalio's curator insight, February 18, 2014 6:56 AM

Muito interessante. Carol, Ina e Paulo, acho este paper importante pro projeto de vcs!

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Enhanced disease resistance caused by BRI1 mutation is conserved between Brachypodium distachyon and barley (Hordeum vulgare).

Enhanced disease resistance caused by BRI1 mutation is conserved between Brachypodium distachyon and barley (Hordeum vulgare). | Biotic | Scoop.it

Mutation of BdBRI1 and HvBRI1 enhances resistance to Magnaporthe oryzae

 


Via Elsa Ballini
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Genome-Wide Evolutionary Characterization and Expression Analyses of WRKY Family Genes in Brachypodium distachyon

Genome-Wide Evolutionary Characterization and Expression Analyses of WRKY Family Genes in Brachypodium distachyon | Biotic | Scoop.it

It has been demonstrated that WRKY genes were not only involved in the activation of plant defence systems, but also played key roles in the control of plants' response to environmental stimuli.

For phytopathogen treatment, 2-week-old seedlings were sprayed with Fusarium graminearum (F0968) and two strains of Magnaporthe grisea (Guy11, avirulent ACE1 genotype; PH14, virulent ACE1 genotype) for 4 or 12 h. The BdWRKY array constituted of 86 primer sets representing all members of the B. distachyon WRKY gene family. The expression of the 86 BdWRKY genes was assessed upon the qPCR result analysis.

The results showed that the expression of BdWRKY genes was rapidly regulated by stresses and phytohormones, and there was a strong correlation between promoter cis-elements and the phytohormones-induced BdWRKY gene expression.


Via Elsa Ballini, Ricardo Oliva
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Regulation of Cellular Diacylglycerol through Lipid Phosphate Phosphatases Is Required for Pathogenesis of the Rice Blast Fungus, Magnaporthe oryzae

Regulation of Cellular Diacylglycerol through Lipid Phosphate Phosphatases Is Required for Pathogenesis of the Rice Blast Fungus, Magnaporthe oryzae | Biotic | Scoop.it

Considering implication of diacylglycerol in both metabolism and signaling pathways, maintaining proper levels of diacylglycerol (DAG) is critical to cellular homeostasis and development. Except the PIP2-PLC mediated pathway, metabolic pathways leading to generation of DAG converge on dephosphorylation of phosphatidic acid catalyzed by lipid phosphate phosphatases. Here we report the role of such enzymes in a model plant pathogenic fungus, Magnaporthe oryzae. We identified five genes encoding putative lipid phosphate phosphatases (MoLPP1 to MoLPP5). Targeted disruption of four genes (except MoLPP4) showed that MoLPP3 and MoLPP5 are required for normal progression of infection-specific development and proliferation within host plants, whereas MoLPP1 and MoLPP2 are indispensable for fungal pathogenicity. Reintroduction of MoLPP3 and MoLPP5 into individual deletion mutants restored all the defects. Furthermore, exogenous addition of saturated DAG not only restored defect in appressorium formation but also complemented reduced virulence in both mutants. Taken together, our data indicate differential roles of lipid phosphate phosphatase genes and requirement of proper regulation of cellular DAGs for fungal development and pathogenesis.


Via Elsa Ballini
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MPMI: Identification and Characterization of In-planta Expressed Secreted Effectors from Magnaporthe oryzae that Induce Cell Death in Rice (2012)

MPMI: Identification and Characterization of In-planta Expressed Secreted Effectors from Magnaporthe oryzae that Induce Cell Death in Rice (2012) | Biotic | Scoop.it

Interactions between rice and Magnaporthe oryzae involve the recognition of cellular components and the exchange of complex molecular signals from both partners. How these interactions occur in rice cells is still elusive. We employed robust-long serial analysis of gene expression (RL-SAGE), massively parallel signature sequencing (MPSS), and sequencing by synthesis (SBS), to examine transcriptome profiles of infected rice leaves. A total of 6,413 in-planta expressed fungal genes including 851 genes encoding predicted effector proteins were identified. We used a protoplast transient expression system to assess 42 of the predicted effector proteins for the ability to induce plant cell death. Ectopic expression assays identified five novel effectors that induced host cell death only when they contained the signal peptide for secretion to the extracellular space. The five apoplastic effectors induced cell death in a non-host-selective-manner. Although the five effectors are highly diverse in their sequences, the physiological basis of cell death induced by each was similar. This study demonstrates that our integrative genomic approach is effective for the identification of in-planta expressed cell death-inducing effectors from M. oryzae that may play an important role facilitating colonization and fungal growth during infection.


Via Kamoun Lab @ TSL, Elsa Ballini, Ricardo Oliva
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PLOS ONE: Interfamily Transfer of Dual NB-LRR Genes Confers Resistance to Multiple Pathogens (2013)

PLOS ONE: Interfamily Transfer of Dual NB-LRR Genes Confers Resistance to Multiple Pathogens (2013) | Biotic | Scoop.it

A major class of disease resistance (R) genes which encode nucleotide binding and leucinerich repeat (NB-LRR) proteins have been used in traditional breeding programs for crop protection. However, it has been difficult to functionally transfer NB-LRR-type R genes in taxonomically distinct families. Here we demonstrate that a pair of Arabidopsis (Brassicaceae) NB-LRR-type R genes, RPS4 and RRS1, properly function in two other Brassicaceae, Brassica rapa and Brassica napus, but also in two Solanaceae, Nicotiana benthamiana and tomato (Solanum lycopersicum). The solanaceous plants transformed with RPS4/RRS1 confer bacterial effector-specific immunity responses. Furthermore, RPS4 and RRS1, which confer resistance to a fungal pathogen Colletotrichum higginsianum in Brassicaceae, also protect against Colletotrichum orbiculare in cucumber (Cucurbitaceae). Importantly, RPS4/RRS1transgenic plants show no autoimmune phenotypes, indicating that the NB-LRR proteins are tightly regulated. The successful transfer of two R genes at the family level implies that the downstream components of R genes are highly conserved. The functional interfamily transfer of R genes can be a powerful strategy for providing resistance to a broad range of pathogens.


Via Kamoun Lab @ TSL, Ricardo Oliva
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PNAS: Activation of dimeric ABA receptors elicits guard cell closure, ABA-regulated gene expression, and drought tolerance

PNAS: Activation of dimeric ABA receptors elicits guard cell closure, ABA-regulated gene expression, and drought tolerance | Biotic | Scoop.it

Nice work - a new ABA agonist identified, quinabactin, that preferentially interacts with a subsest of ABA receptors and confers drought-stress tolerance.


Via Mary Williams, Ricardo Oliva
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Modulation of plant immunity by light, circadian rhythm, and temperature

Modulation of plant immunity by light, circadian rhythm, and temperature | Biotic | Scoop.it

Via Elsa Ballini, Ricardo Oliva
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Elsa Ballini's curator insight, September 26, 2013 7:35 AM

Similarly, high temperature induces expression of rice blast resistance Pib R genes, and this transcriptional upregulation is likely responsible for enhanced resistance to the rice blast fugus at higher temperatures. In sum, temperature seemingly exerts its effect on disease resistance by regulating the expression and activities of key defense components.

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Heterotrimeric g proteins in plant defense against pathogens and aba signaling

Heterotrimeric g proteins in plant defense against pathogens and aba signaling | Biotic | Scoop.it

Via Elsa Ballini
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