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Rice Blast
Scientific articles on rice blast and wheat blast 20 new articles each month !
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The NB-LRR proteins RGA4 and RGA5 interact functionally and physically to confer disease resistance

The NB-LRR proteins RGA4 and RGA5 interact functionally and physically to confer disease resistance | Rice Blast | Scoop.it

Plant resistance proteins of the class of nucleotide-binding and leucine-rich repeat domain proteins (NB-LRRs) are immune sensors which recognize pathogen-derived molecules termed avirulence (AVR) proteins. We show that RGA4 and RGA5, two NB-LRRs from rice, interact functionally and physically to mediate resistance to the fungal pathogen Magnaporthe oryzae and accomplish different functions in AVR recognition. RGA4 triggers an AVR-independent cell death that is repressed in the presence of RGA5 in both rice protoplasts andNicotiana benthamiana. Upon recognition of the pathogen effector AVR-Pia by direct binding to RGA5, repression is relieved and cell death occurs. RGA4 and RGA5 form homo- and hetero-complexes and interact through their coiled-coil domains. Localization studies in rice protoplast suggest that RGA4 and RGA5 localize to the cytosol. Upon recognition of AVR-Pia, neither RGA4 nor RGA5 is re-localized to the nucleus. These results establish a model for the interaction of hetero-pairs of NB-LRRs in plants: RGA4 mediates cell death activation, while RGA5 acts as a repressor of RGA4 and as an AVR receptor.

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A Quick and Accurate Screening Method for Fungal Gene-deletion Mutants by Direct, Priority-based, and Inverse PCR

A Quick and Accurate Screening Method for Fungal Gene-deletion Mutants by Direct, Priority-based, and Inverse PCR | Rice Blast | Scoop.it

The validity of this redesigned process was confirmed using the rice blast fungus,Magnaporthe oryzae, as a model.


• Fungal gene-deletion mutants are quickly selected via two-step-PCR screening.

• Direct PCR allows rapid screening by omitting the genomic DNA extraction step.

• Priority-based PCR helps to avoid false-negatives in selecting mutant candidates.

• Inverse PCR sufficiently replaces Southern blotting to confirm successful TGR.


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Formulations for paddy rice fields - BASF Patent

The present invention relates to microcapsules, formulations comprising such microcapsules and to methods of combating phytopathogenic pests in paddy rice fields based on such microcapsules.
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OsNAC111, a blast disease-responsive transcription factor in rice, positively regulates the expression of defense-related genes

OsNAC111, a blast disease-responsive transcription factor in rice, positively regulates the expression of defense-related genes | Rice Blast | Scoop.it

We identified a transcription factor in rice, OsNAC111, belonging to the TERN subgroup of the NAC family that was transcriptionally upregulated after rice blast fungus inoculation. Transgenic rice plants overexpressing OsNAC111 showed increased resistance to the rice blast fungus. In OsNAC111-overexpressing plants, the expression of several defense-related genes including pathogenesis-related (PR) genes was constitutively high compared with the control. These genes all showed blast disease-responsive expression in leaves. These results indicate that OsNAC111 positively regulates the expression of a specific set of PR genes in the disease response and contributes to disease resistance.

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Development and Characterization of Rice Mutants for Functional Genomics Studies and Breeding

Development and Characterization of Rice Mutants for Functional Genomics Studies and Breeding | Rice Blast | Scoop.it

Approximately 100 000 putative mutants of rice (Oryza sativa L.) have been generated by mutagens. Mutant genes involved in plant architecture, grain quality and disease resistance have been isolated and characterized. In this review, we described the ethyl methanesulfonate (EMS), irradiation, and fast neutron methods used to create rice mutants; methods for the analysis of rice genes that are responsible for mutations; the use of new mutants for rice breeding and functional genomics; and the molecular mechanisms of blast resistance gene-mediated defence responses.

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Characteristics and safety assessment of intractable proteins in genetically modified crops

Characteristics and safety assessment of intractable proteins in genetically modified crops | Rice Blast | Scoop.it

“Intractable proteins” in GM crops cannot be isolated or studied by existing methods.

Intractability results from low expression, membrane association, or other factors.

The established tiered weight-of-evidence approach can be used for safety assessment.

No protein is needed for history of safe use (HOSU) and bioinformatics analyses.

Enriched or substitute proteins may offer alternatives to pure protein dose testing.

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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 | Rice Blast | Scoop.it
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Developing Maganporthe oryzae conidia

These spores were suspended on a growth medium supplemented with 1,16-hexadecanediol (HDD). HDD is an inducer of appressorium formation. Appressorium is an important structure in Magnaporthe,...
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Genome-Wide Analysis of the NADK Gene Family in Plants

Genome-Wide Analysis of the NADK Gene Family in Plants | Rice Blast | Scoop.it

We performed a comparative genomic analysis that identified 74 NADK gene homologs from 24 species representing the eight major plant lineages within the supergroup Plantae: glaucophytes, rhodophytes, chlorophytes, bryophytes, lycophytes, gymnosperms, monocots and eudicots. OsNADK genes is induced to varying degrees by abiotic stress such as cold, heat, drought (PEG), salt (NaCl) and oxidative (methyl viologen, MV), as well as by biotic stress such as the pathogens Magnaporthe oryzae.

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Identification of antagonist molds against Pyricularia oryzae using internal transcribed spacers (ITS)

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Transgenic cereals: Current status and future prospects

Related results from rice include resistance to rice blast (Magnaporthe oryzae) in lines expressing a chimeric receptor consisting of the rice chitin oligosaccharides binding protein (CEBiP) and the intracellular protein kinase region of Xa21. Similarly lines expressing the WRKY30 gene or inducible ethylene production showed improved resistance to rice blast and rice sheath blast (Rhizoctonia solani), and lines expressing a bacterial α-1,3-glucanase (AGL-rice) showed strong resistance not only to the two blast pathogens but also to the phylogenetically distant ascomycete Cochlioborus miyabeanus.

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Design, Synthesis and Bioactivity of Novel Glycosylthiadiazole Derivatives

A series of novel glycosylthiadiazole derivatives, namely 2-phenylamino-5-glycosyl-1,3,4-thiadiazoles, were designed and synthesized by condensation between sugar aldehydes A/B and substituted thiosemicarbazide C followed by oxidative cyclization by treating with manganese dioxide. The original fungicidal activities results showed that some title compounds exhibited excellent fungicidal activities against Sclerotinia sclerotiorum (Lib.) de Bary and Pyricularia oryzae Cav.

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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 | Rice Blast | 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.

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The Natural Product Citral Can Cause Significant Damage to the Hyphal Cell Walls of Magnaporthe grisea

The Natural Product Citral Can Cause Significant Damage to the Hyphal Cell Walls of Magnaporthe grisea | Rice Blast | Scoop.it

In order to find a natural alternative to the synthetic fungicides currently used against the devastating rice blast fungus, Magnaporthe grisea, this study explored the antifungal potential of citral and its mechanism of action. It was found that citral not only inhibited hyphal growth of M. grisea, but also caused a series of marked hyphal morphological and structural alterations. Furthermore, citral reduced spore germination and germ tube length in a concentration-dependent manner. Following exposure to citral, the hyphal cell surface became wrinkled with folds and cell breakage that were observed under scanning electron microscopy (SEM). There was damage to hyphal cell walls and membrane structures, loss of villous-like material outside of the cell wall, thinning of the cell wall, and discontinuities formed in the cell membrane following treatment based on transmission electron microscopy (TEM). 

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An expedited method for isolation of DNA for PCR from Magnaporthe oryzae stored on filter paper

An expedited method for isolation of DNA for PCR from Magnaporthe oryzae stored on filter paper | Rice Blast | Scoop.it

The fungus Magnaporthe oryzae is the causal agent of a wide range of cereal diseases. For long-term preservation, the fungus is grown and stored desiccated on filter papers at –20 °C. Inoculated filter papers are cut into pieces of 0.5–1.0 cm diameter prior to storage. In the present study, a fast (11 min) and simple method of preparing DNA suitable for amplifying avirulence genes of M. oryzae by polymerase chain reaction (PCR) was developed. A piece of filter paper containing the fungus was removed from a glass bottle and placed in a 0.2 mL Eppendorf tube containing 100 μL 10 × TE. The suspension was heated for 10 min at 95 °C in a PCR machine. The tube was then centrifuged for 1 min at 3000 r min–1. One μL of 10 × TE solution containing DNA was used for PCR. A total of 28 samples were PCR tested. As a positive control, fungal DNA was extracted using a conventional DNA preparation method. DNA samples obtained from both methods were stored at 4 °C. PCR was performed with DNA on the preparation day and after 4, 8, 10, and 18 days of refrigerated storage. In four samples, samples 12, 13, 14, and 28, AVR-Pi9 failed to be amplified. These four samples were tested with a different set of primers for AVR-Pi9, and for AVR-Pita1, confirming that the quality of the samples was insufficient for PCR. Overall, for nearly 90% (24/28) of the samples, the quality of the DNA prepared directly from the fungus on filter paper appeared suitable for a rapid survey of genetic identity of the rice blast fungus by PCR. This method will be useful and effective for reducing cost and time and could readily be adopted worldwide for analysis of M. oryzae and possibly other fungi.

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Fungal model systems and the elucidation of pathogenicity determinants

Fungal model systems and the elucidation of pathogenicity determinants | Rice Blast | Scoop.it

• History of seven fungal species used as models for studying development and pathogenicity.

• Outline of central stages of their life cycle and their infection processes.

• Molecular toolkits used to study different aspects of pathogenicity.

• Insight gained from genome sequencing projects.

• Current research trends and future challenges.

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Limonoid derivatives and its pesticidal activities

Diverse pesticidal activities of anthothecol derived from Khaya anthotheca (Meliaceae) and three limonoids (gedunin, limonin and obacunone) were determined using six phytopathogenic fungi (Pyricularia grisea, Rhizoctonia solani, Botrytis cinerea,. Puccinia recondita, Phytophthora, ... ) and four insect pests (Plutella xylostella).

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Potentialities of associated diazotrophic bacteria in plant growth promotion and biocontrol of Pyricularia oryzae (Sacc.) in rice (Oryza sativa L.).

Associated diazotrophic bacteria have been shown to contribute with fixed atmospheric nitrogen to the rice crop making possible to reduce the application of nitrogen fertilizers, limiting with it the growth of Pyricularia oryzae. In addition, the metabolites released by these bacteria in the rhizosphere make the plague concentration and the disease severity decrease leading to the reduction of chemical product applications and a lower incidence of rice blast under field conditions. Cuban autochthonous strains have the ability to control Pyricularia oryzae in vitro, which confirms the fact that associated diazotrophic bacteria stimulate plant growth and mitigate the deleterious effects caused by this disease in rice.

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XVI IS-MPMI 2014, Rhodes, Greece

TYROSINE DEPHOSPHORYLATION OF OSMPK6 IS A NODE OF ABSCISIC-ACID-MEDIATED SUPPRESSION OF SALICYLIC-ACID DEFENSE SIGNALING IN RICE

Phosphorylation/activation of a rice mitogen-activated protein kinase (MAPK), OsMPK6, by dexamethasone-induced expression of constitutively active OsMKK10-2 mimicked the activation of the SA pathway in rice, leading to blast resistance dependent on WRKY45, the central transcription factor in the rice SA pathway. Conversely, ABA treatment dephosphorylated OsMPK6 at its tyrosine residue in rice seedlings. Two protein tyrosine phosphatases, OsPTP1 and -2 were found to dephosphorylate and inactivate OsMPK6 in vitro. In wild-type rice, low temperature, as well as ABA, suppressed the blast resistance induced by a chemical defense inducer, benzothiadiazole. However, simultaneous knockdown of OsPTP1 and -2 by RNA interference abolished the suppression of benzothiadiazole-induced blast resistance by both ABA and low temperature. These results not only show that tyrosine dephosphorylation of OsMPK6 by PTPases is a node of the antagonistic interaction of cold-induced ABA signaling against SA defense signaling in rice, but also provides an effective way to prevent the damages by blast disease under low temperature.

 

RECOGNITION OF THE MAGNAPORTHE ORYZAE EFFECTOR AVRPIZ-T BY MULTIPLE HOST TARGETS IN RICE

In the last few years, we have applied an integrated approach to dissecting the AvrPiz-t and Piz-t interaction and identified several AvrPiz-t-interacting proteins (APIPs). Among them, APIP6, a RING finger E3 ligase, degrades AvrPiz-t and is a positive regulator of PAMP-triggered
immunity (PTI). APIP5 encodes a transcription factor and negatively regulates cell death and disease resistance to M. oryzae. 

 

CHEMICAL COMMUNICATION INVOLVED IN MAGNAPORTHE-RICE INTERACTION DURING INITIATION OF BLAST DISEASE

Recently, we identified a “pathogenicity island” in the vicinity of the ABC3 locus that harbors a Polyketide Synthase and a Cytochrome P450-related locus essential for Magnaporthe pathogenesis. Loss of PKS1 leads to hypermelanized appressoria and defects in septin localization and penetration pore formation. Pks1-GFP is cytosolic and present exclusively in the appressoria. Inhibition of melanin synthesis affects Pks1-GFP expression and localization. Thus, it is likely that a substrate of Pks1 is essential for host penetration and is shared with the melanin biosynthesis pathway.

INFECTION ASSOCIATED AUTOPHAGY IS INDEPENDENT OF APOPTOSIS AND SUFFICIENT FOR APPRESSORIUM-MEDIATED PLANT INFECTION BY MAGNAPORTHE ORYZAE

 

Here, we show that ultrastructural and biochemical changes characteristic of apoptosis occur in a M. oryzae in response to pro-apototic stimuli. We identified a number of apoptosis associated genes in M.oryzae and targeted these gene for deletion to determine whether their lack of function has any physiological consequences for the fungus in terms of its response to stress, and in its capacity to infect. M.oryzae has two metacaspase genes MCP1 and MCP2. We found that the single deletion mutants mcp1 and mcp2 and the double mutant mcp1/mcp2 were not affected in their sensitivity to a range of pro-apoptotic stimuli but did show reduced growth in the presence of agents that disrupt endoplasmic reticulum homeostasis, and in addition were fully pathogenic. We have also deleted a number of genes associated with caspase independent apoptosis. These mutants all resulted in an altered response to various apoptotic stresses but retained wild-type virulence. We conclude that although apoptosis occurs in M.oryzae the cell death of the conidium which is a pre-requisite for infection is accomplished solely by autophagy.

 

MAGNAPORTHE - RICE INTERACTIONS AS REVEALED BY WHOLE GENOME ANALYSIS

 

Using whole genome information of M. oryzae and rice, we isolated AVR-Pia, AVR-Pii, AVR-Pik and cognate R-genes Pia and Pii. In this talk, I introduce whole genome sequence (WGS)-based gene isolation methodologies including MutMap and report our latest findings on the interaction between AVR-Pik and Pik.

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Involvement of the OsMKK4-OsMPK1 Cascade and its Downstream Transcription Factor OsWRKY53 in the Wounding Response in Rice

The activation of the same 48-kDa MAPK was also
observed as the top band among three bands in rice leaves
that were treated with rice blast fungus, Magnaporthe
grisea

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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). | Rice Blast | Scoop.it

Mutation of BdBRI1 and HvBRI1 enhances resistance to Magnaporthe oryzae

 

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Roles of Forkhead-box Transcription Factors in Controlling Development, Pathogenicity, and Stress Response in Magnaporthe oryzae

Deletion of MoFKH1 (ΔMofkh1) resulted in reduced mycelial growth and conidial germination, abnormal septation and stress response, and reduced virulence. Similarly, ΔMohcm1 exhibited reduced mycelial growth and conidial germination. On the other hand, loss of MoFOX1 (ΔMofox1) did not show any noticeable changes in development, pathogenicity, and stress response. Deletion of MoFOX2 was not successful even after repeated attempts. Taken together, these results suggested that MoFKH1 and Mo- HCM1 are important in fungal development and that MoFKH1 is further implicated in pathogenicity and stress response in M. oryzae.

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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 | Rice Blast | 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
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Targeted gene disruption of OsCERK1 reveals its indispensable role in chitin perception and involvement in the peptidoglycan response and immunity in rice

Targeted gene disruption of OsCERK1 reveals its indispensable role in chitin perception and involvement in the peptidoglycan response and immunity in rice | Rice Blast | Scoop.it

OsCERK1 is a rice receptor-like kinase that mediates the signal of a fungal cell wall component, chitin, by coordinating with a lysin motif (LysM)-containing protein, CEBiP. To further elucidate the function of OsCERK1 in the defense response, we disrupted OsCERK1. In OsCERK1-disrupted lines, the generation of hydrogen peroxide and the alteration of gene expression in response to a chitin oligomer were completely abolished. The OsCERK1-disrupted lines also showed lowered responsiveness to a bacterial cell wall component, peptidoglycan. Yeast two-hybrid analysis indicated that OsCERK1 interacts with the LysM-containing proteins, LYP4 and LYP6, which are known to participate in the peptidoglycan response in rice. Observation of the infection behavior of rice blast fungus (Magnaporthe oryzae) revealed that disruption of OsCERK1 led to increased hyphal growth in leaf sheath cells. GFP-tagged OsCERK1 was localized around the primary infection hyphae. These results demonstrate that OsCERK1 is indispensable for chitin perception and participates in innate immunity in rice, and also mediates the peptidoglycan response. It is also suggested that OsCERK1 mediates the signaling pathways of both fungal and bacterial molecular patterns by interacting with different LysM-containing receptor-like proteins.

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Genotyping and development of single-nucleotide polymorphism (SNP) markers associated with blast resistance genes in rice using GoldenGate assay

Genotyping and development of single-nucleotide polymorphism (SNP) markers associated with blast resistance genes in rice using GoldenGate assay | Rice Blast | Scoop.it

In the present study, Illumina GoldenGate assay was used to validate and genotype SNPs in a set of six major rice blast resistance genes: Pi-ta, Piz(t), Pi54, Pi9, Pi5(1)and Pib. All the selected SNPs loci (96) were genotyped successfully in 92 rice lines with an overall genotype call rate of 92.0 % and minimum GenTrain cutoff score of ≥0.448. Minor allele frequency ranged from 0.01 to 0.49 and has good differentiating power for distinguishing different rice accessions. SNPs markers were validated in a set of 92 rice lines and converted into CAPS markers which can be used in blast resistance breeding programme.

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