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PLOS Genetics: Approaching the Functional Annotation of Fungal Virulence Factors Using Cross-Species Genetic Interaction Profiling

PLOS Genetics: Approaching the Functional Annotation of Fungal Virulence Factors Using Cross-Species Genetic Interaction Profiling | Rice Blast | Scoop.it

HIV/AIDS patients, cancer chemotherapy patients, and organ transplant recipients are highly susceptible to infection by opportunistic fungal pathogens, organisms common in the environment that are harmless to normal individuals. Understanding how these pathogens cause disease requires the identification of genes required for virulence and the determination of their molecular function. Our work addresses the latter problem using the yeast Cryptococcus neoformans, which is estimated to cause 600,000 deaths annually worldwide in the HIV/AIDS population. We describe a method for determining gene function in which C. neoformans genes are expressed in deletion mutants of all nonessential genes of the well-studied model yeast S. cerevisiae. By examining the impact on growth (enhancement or suppression) we generated “cross-species” genetic interaction profiles. We compared these profiles to the published genetic interaction profiles of S. cerevisiae deletion mutants to identify those with correlated patterns of genetic interactions. We hypothesized that the known functions of S. cerevisiae genes with correlated profiles could predict the function of the pathogen gene. Indeed, experimental tests in C. neoformans for two pathogenicity genes of previously unknown function found the functional predictions obtained from genetic interaction profiles to be accurate, demonstrating the utility of the cross-species approach.


Via Guogen Yang
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Rice Blast
Scientific articles on rice blast and wheat blast 20 new articles each month !
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Three Wall-Associated Kinases required for rice basal immunity form protein complexes in the plasma membrane

Three Wall-Associated Kinases required for rice basal immunity form protein complexes in the plasma membrane | Rice Blast | Scoop.it
Receptor-like kinases (RLKs) play key roles in disease resistance, in particular basal immunity. They recognize patterns produced by the pathogen invasion and often work as complexes in the plasma membrane. Among these RLKs, there is increasing evidence in several plant species of the key role of Wall-associated kinases (WAKs) in disease resistance. We recently showed using rice (Oryza sativa) loss-of-function mutants of three transcriptionaly co-regulated OsWAK genes that individual OsWAKs are positively required for quantitative resistance to the rice blast fungus, Magnaporthe oryzae. This finding was unexpected since WAK genes belong to large gene families where functional redundancy is expected. Here we provide evidence that this may be due to complex physical interaction between OsWAK proteins.
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Abstract: The Functional Transfer of the Wheat Gene Lr34 into Rice and Its Resistance Against Rice Blast (Plant and Animal Genome XXIV Conference)

Lr34 is a wheat gene which confers a durable, partial and broad spectrum resistance against the three wheat rusts and powdery mildew. Lr34 encodes for an ABC transporter protein and only one resistance-conferring Lr34 allele (Lr34res) has been found in wheat so far. Lr34res evolved as a result of two gain-of-function mutation that occured post domestication, 10000 years ago. Lr34res is only found in cultivated wheat but not in wild wheat progenitor. Consistent with the very recent emergence of Lr34res, an Lr34-like disease resistance with a similar durability and broad-spectrum specificity has not been reported in other important crop species sich as rice or barley. We therefore transformed the wheat Lr34res into rice, one of the most important cereals, and observed that the transgenic lines showed resistance against different rice blast (Magnaporthe oryzae) isolates on a macroscopic and a microscopic level. This hemi-biotrophic fungus is one of the most devastating rice diseases in the world and causes important yield losses every year. Lr34res was shown to provide resistance against biotrophic fungi in wheat but with these results we could show that the spectrum of resistance is even broader, including hemi-biotrophic fungi as well. More interestingly, it was possible to identify one transgenic line with a plant development and some yield parameters comparable to the sister line but with a resistance against rice blast. In the future, Lr34res would be a very useful tool in order to improve disease resistance in rice or other species.
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Three DUF1996 Proteins Localize in Vacuoles and Function in Fungal Responses to Multiple Stresses and Metal Ions

Three DUF1996 Proteins Localize in Vacuoles and Function in Fungal Responses to Multiple Stresses and Metal Ions | Rice Blast | Scoop.it
Many annotated fungal genomes harbour high proportions of hypothetical proteins with or without domains of unknown function (DUF). Here, three novel proteins (342−497 amino acids), each containing only a single large DUF1996 (231−250 residues) region with highly conserved head (DPIXXP) and tail (HXDXXXGW) signatures, were expressed as eGFP-tagged fusion proteins and shown to specifically localize in the vacuoles of Beauveria bassiana, a filamentous fungal entomopathogen; therefore, these proteins were named vacuole-localized proteins (VLPs). The VLPs have one to three homologues in other entomopathogenic or non-entomopathogenic filamentous fungi but no homologues in yeasts. The large DUF1996 regions can be formulated as D-X4-P-X5–6-H-X-H-X3-G-X25–26-D-X-S-X-YW-X-P-X123–203-CP-X39–48-H-X-D-X3-GW; the identical residues likely involve in a proton antiport system for intracellular homeostasis. Single deletions of three VLP-coding genes (vlp1–3) increased fungal sensitivities to cell wall perturbation, high osmolarity, oxidation, and several metal ions. Conidial thermotolerance decreased by ~11% in two Δvlp mutants, and UV-B resistance decreased by 41−57% in three Δvlp mutants. All the changes were restored by targeted gene complementation. However, the deletions did not influence fungal growth, conidiation, virulence or Cu2+ sensitivity. Our findings unveiled a role for the DUF1996 regions of three B. bassiana VLPs in the regulation of multiple stress responses and environmental adaptation
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Integration of decoy domains derived from protein targets of pathogen effectors into plant immune receptors is widespread

Integration of decoy domains derived from protein targets of pathogen effectors into plant immune receptors is widespread | Rice Blast | Scoop.it
Plant immune receptors of the class of nucleotide-binding and leucine-rich repeat domain (NLR) proteins can contain additional domains besides canonical NB-ARC (nucleotide-binding adaptor shared by APAF-1, R proteins, and CED-4 (NB-ARC)) and leucine-rich repeat (LRR) domains. Recent research suggests that these additional domains act as integrated decoys recognizing effectors from pathogens. Proteins homologous to integrated decoys are suspected to be effector targets and involved in disease or resistance.
Here, we scrutinized 31 entire plant genomes to identify putative integrated decoy domains in NLR proteins using the Interpro search. The involvement of the Zinc Finger–BED type (ZBED) protein containing a putative decoy domain, called BED, in rice (Oryza sativa) resistance was investigated by evaluating susceptibility to the blast fungus Magnaporthe oryzae in rice over-expression and knock-out mutants.
This analysis showed that all plants tested had integrated various atypical protein domains into their NLR proteins (on average 3.5% of all NLR proteins). We also demonstrated that modifying the expression of the ZBED gene modified disease susceptibility.
This study suggests that integration of decoy domains in NLR immune receptors is widespread and frequent in plants. The integrated decoy model is therefore a powerful concept to identify new proteins involved in disease resistance. Further in-depth examination of additional domains in NLR proteins promises to unravel many new proteins of the plant immune system.

Via Christophe Jacquet
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A comprehensive catalog of the lysine-acetylation targets in rice (Oryza sativa) based on proteomic analyses

A comprehensive catalog of the lysine-acetylation targets in rice (Oryza sativa) based on proteomic analyses | Rice Blast | Scoop.it

We combined a highly sensitive immune-affinity purification method with high-resolution LC-MS/MS. In total, we identified 1337 Kac sites on 716 Kac proteins in rice cells. To our knowledge, the number of Kac sites we identified was 23-times greater and the number of Kac proteins was 16-times greater than in a previous report.
Bioinformatic analysis of the acetylome revealed that the acetylated proteins are involved in a variety of cellular functions and have diverse subcellular localizations.
We identified seven putative acetylation motifs in the acetylated proteins of rice.
KEGG pathway category enrichment analysis indicated that glyoxylate and dicarboxylate metabolism, carbon metabolism, and photosynthesis pathways were significantly enriched.
Our results provide an in-depth understanding of the acetylome in rice seedlings, and the method described here will facilitate the systematic study of how Kac functions in growth, development and responses to abiotic and biotic stresses in rice or other plants.

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Synthesis and Biological Evaluation of Novel Inhibitors against 1,3,8-trihydroxynaphthalene Reductase from Magnaporthe grisea

Synthesis and Biological Evaluation of Novel Inhibitors against 1,3,8-trihydroxynaphthalene Reductase from Magnaporthe grisea | Rice Blast | Scoop.it
1,3,8-trihydroxynaphthalene reductase (3HNR) is an essential enzymes that is involved in fungal melanin biosynthesis. Based on the structural informations of active site of 3HNR, a series of β-Nitrostyrene compounds were rationally designed and synthesized. The enzymatic activities of these compounds showed that most of them exhibited high inhibitory activities (< 5.0 μM) against 3HNR; Compound 3-2 exhibit the highest inhibitory activity (IC50 = 0.29 μM). In particular, some of these compounds had moderate fungicidal activity against M. grisea. Compound 3-4 showed high in vivo activities against M. grisea (EC50 = 9.5 ppm). Furthermore, Compound 3-2 was selected as a representative molecule, and the probable binding mode of this compound and the surrounding residues in the active site of 3HNR was elucidated by using molecular dock. The positive results suggest that β-Nitrostyrene Derivatives are most likely to be promising leads toward the discovery of novel agent of rice blast.
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Science Signaling: 2015: Signaling Breakthroughs of the Year - Plant Innate Immune Response

Science Signaling: 2015: Signaling Breakthroughs of the Year - Plant Innate Immune Response | Rice Blast | Scoop.it

Plants are subject to attack by pathogens, and, like animals, the plant innate immune response involves both surface and cytoplasmic receptors. Intracellular nucleotide-binding leucine-rich repeat receptors involved in the plant innate immune response are structurally and functionally similar to animal Nod-like receptors (NLRs), which play a key role in inflammasome activation. Plant NLRs, which detect pathogen-derived virulence factors (effectors) frequently directed against plant defenses triggered by the plasma membrane-localized immune receptors, can function in pairs, with both partners required for activation of an immune response. In work that he described as representing “a paradigmatic shift in our understanding of how immune receptors work,” Cyril Zipfel nominated three papers (24–26) describing an intriguing twist on effector detection. Le Roux et al. (24) and Sarris et al. (25) showed how integration of a “decoy” or “sensor” domain that mimics host targets baits pathogenic virulence factors to one member of a plant NLR pair, thereby activating the partner NLR to initiate defense signaling. In a third breakthrough paper on this theme, Maqbool et al. (26) determined the structural basis for effector interaction with a different class of integrated domain and demonstrated that a high binding affinity between the NLR domain and the effector is required to activate immunity. The emerging theme from these papers is that the very mechanisms that enable pathogen virulence factors to cripple the initial wave of the immune response have been turned to their own destruction.


Via Kamoun Lab @ TSL, Steve Marek, Jennifer Mach
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Septation and Cytokinesis in Pathogenic Fungi

The control of cytokinesis and septation by pathogenic fungi is critical to the developmental changes associated with host invasion and fungal pathogenesis. Pathogenic processes, such as growth within host tissue, often require changes between yeast-like, determinate, isotropic growth and hyphal, polarised, anisotropic growth, which must be appropriately regulated in concert with nuclear division. In plant pathogenic fungi, a body of evidence, primarily generated from studies of the rice blast fungus M. oryzae, shows that septin-mediated remodelling of the actin cytoskeleton is fundamental to the action of its specialised infection cells, called appressoria, during plant infection. Future studies will need to ask several questions which logically follow these recent discoveries. First of all, is the role of septin GTPases in appressorium repolarisation regulated distinctly from their role in each round of septation within vegetative and invasive hyphae? For example, is there a turgor-sensing mechanism that regulates septin ring formation only once the required turgor has been generated in the infection structure to breach the plant cuticle? Is the regulated synthesis of reactive oxygen species, which is essential for septin assembly in M. oryzae appressoria, a common mechanism by which septin-dependent processes are regulated in fungi? Can this explain why regulated bursts of ROS are often associated with cellular differentiation in fungi, such as fruit body formation and sporulation? Are the processes identified in M. oryzae appressorium development highly conserved among appressorium-forming fungi, such as the rusts, anthracnose-causing fungi and the powdery mildews? If so, can we find evidence for common mechanisms that regulate appressorium-mediated plant infection, such as the conserved MAP kinase cascades (Perez-Nadales et al. 2014), that might be targeted to develop broad spectrum anti-penetrant fungicides? Finally, it is clear that there are important parallels between the way in which yeast budding operates and the operation of fungal appressoria, particularly in the processes leading up to penetration peg formation and repolarisation. Some of the most conserved components probably play similar roles. Clearly, there are important differences as well, not least of all in the enormous invasive forces deployed by appressoria, but the conserved components involved in some of these processes can provide an important roadmap to test hypotheses and define the fundamental mechanisms by which infection structures work in plant pathogenic fungi.
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Overexpression of Rice Wall-Associated Kinase 25 (OsWAK25) Alters Resistance to Bacterial and Fungal Pathogens

Overexpression of Rice Wall-Associated Kinase 25 (OsWAK25) Alters Resistance to Bacterial and Fungal Pathogens | Rice Blast | Scoop.it
Wall-associated kinases comprise a sub-family of receptor-like kinases that function in plant growth and stress responses. Previous studies have shown that the rice wall-associated kinase, OsWAK25, interacts with a diverse set of proteins associated with both biotic and abiotic stress responses. Here, we show that wounding and BTH treatments induce OsWAK25 transcript expression in rice. We generated OsWAK25 overexpression lines and show that these lines exhibit a lesion mimic phenotype and enhanced expression of rice NH1 (NPR1 homolog 1), OsPAL2, PBZ1 and PR10. Furthermore, these lines show resistance to the hemibiotrophic pathogens, Xanthomonas oryzae pv. oryzae (Xoo) and Magnaporthe oryzae, yet display increased susceptibility to necrotrophic fungal pathogens, Rhizoctonia solani and Cochliobolus miyabeanus.

Via Christophe Jacquet, Guogen Yang
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A novel L-arabinose-responsive regulator discovered in the rice-blast fungus Pyricularia oryzae (Magnaporthe oryzae)

In this study we identified the L-arabinose-responsive regulator of Pyricularia oryzae that regulates L-arabinose release and catabolism. Previously we identified the Zn2Cys6 transcription factor (TF) AraR that has this role in the Trichocomaceae family (Eurotiales), but is absent in other fungi.

Candidate Zn2Cys6 TF genes were selected according to their transcript profiles on L-arabinose. Deletion mutants of these genes were screened for their growth phenotype on L-arabinose. One mutant, named Δara1, was further analyzed. Our analysis demonstrated that Ara1 from P. oryzae is the functional analog of AraR from A. niger, while there is no significant sequence similarity between them.
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37th New Phytologist Symposium, Beijing, China 15-19 May 2016

37th New Phytologist Symposium, Beijing, China 15-19 May 2016 | Rice Blast | Scoop.it

Plant developmental evolution.

 

The relatively new field of plant evolutionary-developmental biology (‘evo-devo’) seeks to understand how and why plant morphological characters have evolved to produce the tremendous diversity of form in living plants. It draws from concepts and techniques of molecular biology, developmental biology, genetics, genomics, evolutionary biology and ecology, and attempts to synthesize principles from these disciplines to yield an understanding of how developmental systems respond to selection pressures for novel characters. It also seeks to characterize how evolution moulds complex traits, as well as the constraints that prevent such traits from reaching ‘optimal’ configurations. This meeting will draw together researchers in plant evo-devo for exchange of ideas, information about current research, and discussion of future directions for the field.  It will be organised into four sessions; three will be devoted to (1) floral development, (2) vegetative meristems, leaves, and inflorescences, and (3) plasticity and life history evo-devo and a fourth morning will be devoted to speakers who have been selected to give a talk following the submission of a poster abstract.  - See more at: https://www.newphytologist.org/symposia/37#sthash.lL8Vql5j.dpuf

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Infection process of Pyricularia oryzae on the leaves of wheat seedlings

The aim of this study was to use scanning electron microscopy (SEM) to elucidate the infection process of Pyricularia oryzae on leaf surfaces of wheat seedlings. Wheat seedlings were inoculated with a conidial suspension of P. oryzae (105 conidia/mL), and leaf samples were collected for observation via SEM. The first blast symptoms appeared 48 h after inoculation (hai) as small water-soaked lesions. From 72 to 96 hai, these lesions expanded, and intense chlorosis occurred around them. At 120 hai, the lesions became necrotic, adopting a grayish coloration, coalesced and the entire leaf showed signs of tissue death. SEM observations indicated that conidia of P. oryzae began to germinate at 6 hai, and appressoria differentiation occurred at 12 hai. From 12 to 24 hai, wax removal occurred on the leaf surface at the appressorial sites examined. From 36 to 72 hai, conidia and accompanying appressoria appeared to be dehydrated and withered. At 96 hai, leaf tissue adjacent to the fungal hyphae showed signs of degradation. At 120 hai, conidiophores bearing numerous conidia were noticed on the leaf surface. Some conidia germinated next to the conidiophores. This study reports novel information regarding the infection process of P. oryzae on the leaf surfaces of wheat seedlings.
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Rice terpene synthase 24 (OsTPS24) encodes a jasmonate-responsive monoterpene synthase that produces an antibacterial γ-terpinene against rice pathogen

Rice terpene synthase 24 (OsTPS24) encodes a jasmonate-responsive monoterpene synthase that produces an antibacterial γ-terpinene against rice pathogen | Rice Blast | Scoop.it
Rice is one of the most important crops worldwide and is widely used as a model plant for molecular studies of monocotyledonous species. The plant hormone jasmonic acid (JA) is involved in rice-pathogen interactions. In addition, volatile compounds, including terpenes, whose production is induced by JA, are known to be involved in the rice defense system. In this study, we analyzed the JA-induced terpene synthase OsTPS24 in rice. We found that OsTPS24 was localized in chloroplasts and produced a monoterpene, γ-terpinene. The amount of γ-terpinene increased after JA treatment. γ-Terpinene had significant antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo); however, it did not show significant antifungal activity against Magnaporthe oryzae. The antibacterial activity of the γ-terpinene against Xoo was caused by damage to bacterial cell membranes. These results suggest that γ-terpinene plays an important role in JA-induced resistance against Xoo, and that it functions as an antibacterial compound in rice.
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Molecular and cellular analysis of the biotrophic interaction between rice and Magnaporthe oryzae –– Exploring situations in which the blast fungus controls the infection

Molecular and cellular analysis of the biotrophic interaction between rice and Magnaporthe oryzae –– Exploring situations in which the blast fungus controls the infection | Rice Blast | Scoop.it

Characterization of a rice genotype hyper-susceptible to M. oryzae.
Features of symptoms in a hyper-susceptible rice genotype.
Suppression of defense responses in a hyper-susceptible rice genotype.
Transcriptional networks active against fungal infection.
Features of host cellular dynamics during the biotrophic invasion of M. oryzae.
Development of a long-term fluorescence imaging method used to study the biotrophic invasion process.
Close enclosure of invasive hyphae by host vacuolar membranes.
Timing of vacuole disruption and infection.
High-resolution imaging of the biotrophic interfacial complex.

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Genetic analysis and molecular mapping of Pitb with broad-spectrum resistance to Magnaporthe oryzae in rice

Genetic analysis and molecular mapping of Pitb with broad-spectrum resistance to Magnaporthe oryzae in rice | Rice Blast | Scoop.it
Zixuan 2 is a broad spectrum-resistance indica subspecies (Oryza sativa ssp. indica) with a high resistance to 15 Magnaporthe oryzae strains from ZA, ZB, and ZC. The F1 generation of hybrid between Zixuan 2 and Lijiangxintuanheigu showed significant resistance to rice-blast pathogen ZB13, and the ratio of resistant plants to susceptible plants was 3:1, indicating that the resistance of Zixuan 2 to rice blast is controlled by a single dominant karyogene or a quantitative trait locus, designated here as Pitb. Molecular marker analysis showed that the rice blast-resistance gene is located on the terminal short arm of chromosome 12 between IN936 and IN950, with a genetic distance of 3.0 cM and physical distance of 143 kbp. In addition, the localization found that Pitb was coseparated with marker IN937. The genetic data and recombination populations provided in this study will enable further fine-mapping and cloning of the resistance gene.
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Comparative and Functional Genomics Analysis of the Magnaporthales (Plant and Animal Genome XXIV Conference)

The order Magnaporthales includes fungi of great economic importance that cause disease in cereal and turf grasses: Magnaporthe oryzae (rice blast), Gaeumannomyces graminis var. tritici (take-all disease), and Magnaporthe poae (summer patch disease). A genome-scale comparative study was conducted across 74 fungal genomes. Gene clusters involved in transcriptional regulation and enzymatic activities were highly represented in order specific clusters and the species specific genes, suggesting that such proteins may be more plastic and may contribute to speciation. No correlations between diversifying or purifying selection and distance to repetitive elements or an increased rate of evolution in secreted and small secreted proteins were observed. Thus no evidence was found to suggest multi-speed genome evolution or that proximity to repetitive elements plays a role in diversification of genes. Functional analysis was conducted on candidate effectors (small secreted proteins) identified from comparative genome analysis of 40 M. oryzae strains, transcriptome and proteome data. Through a forward genetics screen, 11 suppressors of plant cell death (SPD) were found to inhibit the host cell death reaction induced by the BAX and/or the NPP1 genes within N. benthamiana. Four were previously identified as either essential for pathogenicity of M. oryzae, secreted into the plant during disease development, or homologues of other characterized suppressors. The others are novel and all remain to be fully characterized.
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OsGF14e positively regulates panicle blast resistance in rice

OsGF14e positively regulates panicle blast resistance in rice | Rice Blast | Scoop.it

GF14e was induced in panicles infected by blast pathogen.
GF14e positively regulate panicle blast resistance in rice.
GF14e-mediated panicle blast resistance is related to SA and JA signaling pathways.
The transcript of GF14e is regulated by WRKY71.

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Molecular and biochemical characterization of rice pectin methylesterase inhibitors (OsPMEIs)

Molecular and biochemical characterization of rice pectin methylesterase inhibitors (OsPMEIs) | Rice Blast | Scoop.it

Forty-nine members of OsPMEI genes showed spatial/temporal expression.
The degree of pectin methylesterification status is developmentally regulated.
Two OsPMEI proteins were biochemically characterized.

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Genetic and molecular analyses of the incompatibility between Lolium isolates of Pyricularia oryzae and wheat

Resistance of common wheat to a Lolium isolate of Pyricularia oryzae was controlled by two genes (one strong and the other weak).
Avirulence of the Lolium isolate on common wheat was controlled by two genes (one strong and the other weak).
Disruption of the strong avirulence gene led the Lolium isolate to gain virulence on common wheat.

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First report of multiple races of rice blast fungus Magnaporthe oryzae in Puerto Rico

The rice nursery located in the Lajas Valley, in the southwestern corner of Puerto Rico has been used by US rice breeders for the past 43 years to produce one to two extra generations per year. In April, 2015, blast disease lesions were observed on rice breeding lines belong to the USDA ARS DB NRRC and to the University of Arkansas Rice Research and Extension Center. The fungal mycelia with three celled asexual spores typical of the rice blast fungus Magnaporthe oryzae were positively identified from diseased panicles. A total of 28 isolates were purified from these lesions, and 20 of which were determined to belong to 4 races, IB1, IB17, IB49, and IB53. Further pathogenicity tests with a set of international differential cultivars and molecular analysis with avirulence gene-specific PCR primers revealed that these isolates were highly similar to isolates commonly found in the USA and the deployed major Pi-ta gene cluster is useful for preventing infections of these isolates. Thus, we show that the Puerto Rico winter nursery serves rice breeders by offering an opportunity to select for blast disease resistance as well as other traits. Although one isolate from Puerto Rico, belonging to IB49, was mentioned in previous literature, the location and time of the occurrence of rice blast has not been reported. To our knowledge this is the first report of rice blast disease in Puerto Rico. In addition, as some commercial production of rice is being re-established on the island, our study suggests that the Pi-ta gene cluster found in a US adapted tropical japonica cultivar Katy will be effective for blast control in Puerto Rico.
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Development of near-isogenic lines with different alleles of Piz locus and analysis of their breeding effect under Yangdao 6 background

Rice blast is one of the most destructive diseases of rice. The most effective way of managing this disease is to develop resistant cultivars by introducing resistance genes into elite rice recipients. In this study, the near-isogenic lines (NILs) of six resistance alleles of the Piz locus (Pizt, Pi2, Pigm, Pi40, Pi9 and Piz) were constructed with Yangdao 6 as genetic background. Seedling inoculation tests showed that most of the NILs, namely NIL-Pi2, NIL-Pigm, NIL-Pi9, NIL-Pizt and NIL-Pi40, exhibited good resistance to blast with resistance frequencies (RFs) of over 82.50 %, execpt NIL-Piz which showed lower resistance with a RF of only 36.13 %. Furthermore, the improved-resistance NILs exhibited high similarity of their resistance spectra, with overlapping degrees of resistance spectrum (OD) of more than 75.83 %. However, the RF of panicle blast for all NILs decreased significantly compared with seedling blast in an artificial inoculation test. Although NIL-Pigm showed a higher panicle blast RF of 80 %, other NILs with outstanding performance in seedling blast resistance, namely NIL-Pizt, NIL-Pi2, NIL-Pi9 and NIL-Pi40, exhibited middle or low RFs of panicle blast with values from 56.67 to 33.30 %. Natural induction in a disease nursery showed a consistent trend in artificial inoculation results at seedling and heading stages. While NIL-Pigm was found to exhibit good resistance to leaf blast and panicle blast, NIL-Pi9 and NIL-Pizt were further demonstrated to show excellent resistance in Suichuan, Jiangxi province and Enshi, Hubei province, respectively, because of the race–region specificity. Agronomic traits of NILs were also investigated in order to evaluate the linkage drag effect of different alleles of the Piz locus. The resistance effects of the different alleles of the Piz locus under identical genetic background against seedling blast and panicle blast was first reported in this study, and the above results are expected to provide a theoretical support for the rational utilization of broad-spectrum resistance genes in breeding practice.
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Orotate phosphoribosyl transferase MoPyr5 is involved in uridine 5′-phosphate synthesis and pathogenesis of Magnaporthe oryzae

Orotate phosphoribosyl transferase (OPRTase) plays an important role in de novo and salvage pathways of nucleotide synthesis and is widely used as a screening marker in genetic transformation. However, the function of OPRTase in plant pathogens remains unclear. In this study, we characterized an ortholog of Saccharomyces cerevisiae Ura5, the OPRTase MoPyr5, from the rice blast fungus Magnaporthe oryzae. Targeted gene disruption revealed that MoPyr5 is required for mycelial growth, appressorial turgor pressure and penetration into plant tissues, invasive hyphal growth, and pathogenicity. Interestingly, the ∆Mopyr5 mutant is also involved in mycelial surface hydrophobicity. Exogenous uridine 5′-phosphate (UMP) restored vegetative growth and rescued the defect in pathogenicity on detached barley and rice leaf sheath. Collectively, our results show that MoPyr5 is an OPRTase for UMP biosynthesis in M. oryzae and indicate that UTP biosynthesis is closely linked with vegetative growth, cell wall integrity, and pathogenicity of fungus. Our results also suggest that UMP biosynthesis would be a good target for the development of novel fungicides against M. oryzae.
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Crystal Structure of Manganese Lipoxygenase of the Rice Blast Fungus Magnaporthe oryzae

Crystal Structure of Manganese Lipoxygenase of the Rice Blast Fungus Magnaporthe oryzae | Rice Blast | Scoop.it
Lipoxygenases (LOX) are non-heme metal enzymes, which oxidize polyunsaturated fatty acids to hydroperoxides. All LOX belong to the same gene family, and they are widely distributed. LOX of animals, plants and prokaryotes contain Fe as the catalytic metal, whereas fungi express LOX with Fe or with Mn. Little is known about metal selection by LOX and the adjustment of the redox potentials of their protein-bound catalytic metals. Thirteen 3D structures of animal, plant, and prokaryotic FeLOX are available but none of MnLOX. The MnLOX of the most important plant pathogen, the rice blast fungus Magnaporthe oryzae (Mo), was expressed in Pichia pastoris. Mo-MnLOX was deglycosylated, purified to homogeneity, and subjected to crystal screening and X-ray diffraction. The structure was solved by sulfur and manganese single-wavelength anomalous dispersion to a resolution of 2.0 Å. The Mn coordinating sphere is similar to Fe ligands of coral 8R-LOX and soybean LOX-1, but not overlapping. The Asn473 is positioned on a short loop (AsnGlnGlyGluPro) instead of an α-helix and forms hydrogen bonds with Gln281. Comparison with Fe-LOX suggest that Phe332 and Phe525 might contribute to the unique suprafacial hydrogen abstraction and oxygenation mechanism of Mo-MnLOX by controlling oxygen access to the pentadiene radical. Modeling suggests that Arg525 is positioned close to Arg182 of 8R-LOX, and both residues likely tether the carboxylate group of the substrate. An oxygen channel could not be identified. We conclude that Mo-MnLOX illustrates a partly unique variation of the structural theme of FeLOX.
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The Economic Impact of Rice Blast Alleviation in the Mid‐South of the United States

The Economic Impact of Rice Blast Alleviation in the Mid‐South of the United States | Rice Blast | Scoop.it
The rice blast fungus, Magnaporthe oryzae, causes extensive damage to rice production globally, which often results in costly fungicide applications and yield losses. These inefficiencies harm farmers via increased costs in production and subsequently drive up food prices for consumers, which can, in turn, give rise to food insecurity in low-income countries. Moreover, there are blast-resistant rice varieties commercially available in the United States; however, breeding for resistance remains problematic because the fungus continuously evolves. In 2013, scientists at Kansas State University identified a blast- resistant gene in a wild rice variety that could be cisgenically transferred into currently cultivated, high- yielding varieties. Due to regulatory protocols on Genetically Modified Organisms in other countries, this technology is not been commercially available to producers. Consequently, the environmental and financial costs of fungicide applications and subsequent yield losses from the rice blast disease, remain high in the United States and other countries. Correspondingly, the aim of this study is to estimate the increased costs for three different rice blast scenarios in the Mid-South of the United States between 2002 and 2014. In the first scenario, we quantified the costs of two preventive fungicide applications to all hectares sown to blast-susceptible varieties; in the second, we quantified the costs of two mitigating fungicide applications on one blast outbreak area that was simulated based on historical outbreaks; and in the third, we quantified the costs of two mitigating fungicide applications on a simulated outbreak with additional yield loss caused by the fungus. The total financial costs of the rice blast disease for all years in each of the three scenarios were $265,691,269, $117,507,463, and $775,071,706 respectively. Overall, these findings necessitate: (1) more research on cisgenic breeding for blast resistance, (2) more robust policy negotiations, and (3) wide-spread adoption by farmers.
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