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Analysis of genetic diversity of Magnaporthe oryzae in Hunan.

The genetic diversity of 169 blast fungus isolates collected from 44 susceptible rice varieties widely grown in 19 locations in Hunan Province was analyzed in 2010 by using 13 pairs of simple sequence repeat (SSR) markers. It was found that these isolates were classified into 8 genetic lineages at 0.8 similar levels, among which L01 was the dominant lineage and its isolates accounted for 66.86% of the total. Most genetic lineages contained isolates from several source areas and many rice varieties. The genetic relationships between the lineages and the source areas and between the lineages and the rice varieties were complex. The isolates from the same locations or from the same varieties had a relatively close genetic relationship, but the differentiation of the blast fungus physiological race varied in different locations. The genetic diversity of M. oryzae was related to the terrain and the number of rice varieties of a location. There was a greater genetic diversity of M. oryzae in mountainous regions with a high elevation than in hilly areas. The more rice varieties planted in a location was, the greater genetic diversity of M. oryzae was.

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Development and evaluation of near-isogenic lines for major blast resistance gene(s) in Basmati rice

Development and evaluation of near-isogenic lines for major blast resistance gene(s) in Basmati rice | Rice Blast | Scoop.it
A set of NILs carrying major blast resistance genes in a Basmati rice variety has been developed. Also, the efficacy of pyramids over monogenic NILs against rice blast pathogen Magnaporthe oryzae has been demonstrated.
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Identification of UV-induced Diterpenes Including a New Diterpene Phytoalexin, Phytocassane F, from Rice Leaves by Complementary GC/MS and LC/MS Approaches

Rice phytoalexins are regarded as one of the most important weapons against pathogenic microorganisms. We attempted to identify novel phytoalexins and their derivatives using GC/MS and LC/MS analyses. Diterpene derivatives, 9β-pimara-7,15-diene-3β,6β,19-triol, 1, stemar-13-en-2α-ol, 2, and 1α,2α-dihydroxy-ent-12,15-cassadiene-3,11-dione, 3, were isolated from UV-irradiated rice leaves by chromatographic methods. These structures were confirmed by 1D- and 2D-NMR and MS analyses. Interestingly, all three compounds were accumulated following an infection by the rice blast pathogen Magnaporthe oryzae. Compounds 1 and 2 exhibited weak antifungal activity and may be the biosynthetic intermediates of rice phytoalexins momilactones and oryzalexin S, respectively. Compound 3 exhibited relatively high inhibitory activity against the fungal mycelial growth of M. oryzae to the same extent as the known phytoalexin phytocassane A. We conclude that 3 is a member of the cassane-type phytoalexin family and propose the name phytocassane F.
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RiceVarMap: a comprehensive database of rice genomic variations

RiceVarMap: a comprehensive database of rice genomic variations | Rice Blast | Scoop.it
Rice Variation Map (RiceVarMap, http:/ricevarmap.ncpgr.cn) is a database of rice genomic variations. The database provides comprehensive information of 6 551 358 single nucleotide polymorphisms (SNPs) and 1 214 627 insertions/deletions (INDELs) identified from sequencing data of 1479 rice accessions. The SNP genotypes of all accessions were imputed and evaluated, resulting in an overall missing data rate of 0.42% and an estimated accuracy greater than 99%. The SNP/INDEL genotypes of all accessions are available for online query and download. Users can search SNPs/INDELs by identifiers of the SNPs/INDELs, genomic regions, gene identifiers and keywords of gene annotation. Allele frequencies within various subpopulations and the effects of the variation that may alter the protein sequence of a gene are also listed for each SNP/INDEL. The database also provides geographical details and phenotype images for various rice accessions. In particular, the database provides tools to construct haplotype networks and design PCR-primers by taking into account surrounding known genomic variations. These data and tools are highly useful for exploring genetic variations and evolution studies of rice and other species.
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Molecular breeding of thermo-sensitive genic male sterile (TGMS) lines of rice for blast resistance using Pi2 gene

Four new TGMS lines with blast resistance gene Pi2 were developed from C815S (an elite TGMS line susceptible to the blast, used as recurrent parent) and VE6219 (a blast resistant line harboring Pi2, used as donor parent). The pathogenicity assays inoculated with 53 blast prevalent isolates in glasshouse showed that the blast resistant frequency of the four TGMS lines was 94.3%-98.1% that is equivalent to blast resistant donor parent VE6219. The field evaluation of the new lines and hybrids made from them at a blast epidemic site also showed high resistant levels against the blast. The genetic background of the newly developed TGMS lines were examined using a whole-genome single nucleotide polymorphism (SNP) array (RICE6K) that turned out more than 83% of the genomic markers were derived from the recurrent parent. The critical temperature points of fertility-sterility alteration of the new TGMS lines were between 22°C and 23°C of daily mean temperature, which is similar to that of C815S. The complete male sterility under natural growth conditions at Wuhan last more than 80 days. Their agronomic and grain quality traits meet the requirement for two-line hybrid rice production.
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Genetic and physical mapping of a new allele of Pik locus from japonica rice ‘Liziangxintuanheigu

Genetic and physical mapping of a new allele of Pik locus from japonica rice ‘Liziangxintuanheigu’ | Rice Blast | Scoop.it
The Chinese rice “Liziangxintuanheigu (LTH)” has been used as a universal susceptible background for the development of international monogenic blast differentials by the JIRCAS–IRRI network. Few reports on the occurrence of LTH incompatible blast isolates from the Philippines and India indicate that the genotype harbours unknown blast resistance gene(s). We report identification, mapping and physical delimitation of the chromosomal location of a new blast resistance gene from LTH. Preliminary linkage analysis of an F2 mapping population generated from a cross between a susceptible cv. ‘Dular’ and LTH localized the blast resistance gene between simple sequence repeat (SSR) markers RM224 and RM6293 on the distal end of the long arm of chromosome 11. Further mapping with polymorphic SSR and sequence tagged site (STS) markers developed from the interval RM224–RM6293 delimited the resistance gene to a 2 cM interval flanked by STS markers STS-7 and STS-13. By aligning the sequences of linked markers on the sequence of cv. Nipponbare, a ~168.05 kb region at the telomeric end of long of chromosome 11 was delineated as the region of the blast resistance gene. Six putatively expressed NBS–LRR genes were identified in the target region by surveying the equivalent genomic region of Nipponbare and two of these, LOC_Os11g46200 and LOC_Os11g46210, were short-listed as a potential candidate for the resistance gene. The new blast resistance gene designated as Pik-l was inferred to be a new allele of Pik locus based on its genomic position and distinct resistance spectra compared to previously known Pik alleles
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Plant NB-LRR proteins: tightly regulated sensors in a complex manner

As plants are sessile, they have evolved hundreds of resistance (R) genes to defend themselves against multiple pathogens. Most of plant R genes encode proteins with the nucleotide-binding and leucine-rich repeat (NB-LRR) domains that interact with pathogen effectors to induce defense responses. Recent findings describing R proteins structures, host interactors and transcriptional and posttranscriptional regulators have broadened our understanding of R gene activity regulation. Genome-wide analyses of NB-LRR genes are useful for identifying host and nonhost R genes and elucidating complex resistance mechanisms. This review provides an overview of the functions of identified NB-LRRs and intra- and intermolecular R gene regulators
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Phylogenomic analysis uncovers the evolutionary history of nutrition and infection mode in rice blast fungus and other Magnaporthales

Phylogenomic analysis uncovers the evolutionary history of nutrition and infection mode in rice blast fungus and other Magnaporthales | Rice Blast | Scoop.it
The order Magnaporthales (Ascomycota, Fungi) includes devastating pathogens of cereals, such as the rice blast fungus Pyricularia (Magnaporthe) oryzae, which is a model in host-pathogen interaction studies. Magnaporthales also includes saprotrophic species associated with grass roots and submerged wood. Despite its scientific and economic importance, the phylogenetic position of Magnaporthales within Sordariomycetes and the interrelationships of its constituent taxa, remain controversial. In this study, we generated novel transcriptome data from 21 taxa that represent key Magnaporthales lineages of different infection and nutrition modes and phenotypes. Phylogenomic analysis of >200 conserved genes allowed the reconstruction of a robust Sordariomycetes tree of life that placed the monophyletic group of Magnaporthales sister to Ophiostomatales. Among Magnaporthales, three major clades were recognized: 1) an early diverging clade A comprised of saprotrophs associated with submerged woods; 2) clade B that includes the rice blast fungus and other pathogens that cause blast diseases of monocot plants. These species infect the above-ground tissues of host plants using the penetration structure, appressorium; and 3) clade C comprised primarily of root-associated species that penetrate the root tissue with hyphopodia. The well-supported phylogenies provide a robust framework for elucidating evolution of pathogenesis, nutrition modes, and phenotypic characters in Magnaporthales
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Dry flowable formulations of antagonistic Bacillus subtilis strain T429 by spray drying to control rice blast disease

Dry flowable formulations of antagonistic Bacillus subtilis strain T429 by spray drying to control rice blast disease | Rice Blast | Scoop.it

Dry flowable formulations of Bacillus subtilis strain T429 were synthesized by spray drying.
Wetting agents, dispersants, disintegrants, and adhesives that show good biocompatibility with B. subtilis T429 were obtained.
Dry flowable formulations were shelf-stable and effective to control rice blast.

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Genome-wide exploration of the molecular evolution and regulatory network of mitogen-activated protein kinase cascades upon multiple stresses in Brachypodium distachyon

Genome-wide exploration of the molecular evolution and regulatory network of mitogen-activated protein kinase cascades upon multiple stresses in Brachypodium distachyon | Rice Blast | Scoop.it

In this study, we have identified MAPKKKs which belong to the biggest gene family of MAPK cascade kinases. We have systematically investigated the evolution of whole MAPK cascade kinase gene family in terms of gene structures, protein structural organization, chromosomal localization, orthologs construction and gene duplication analysis. Our results showed that most BdMAPK cascade kinases were located at the low-CpG-density region, and the clustered members in each group shared similar structures of the genes and proteins. Synteny analysis showed that 62 or 21 pairs of duplicated orthologs were present between B. distachyon and Oryza sativa, or between B. distachyon and Arabidopsis thaliana respectively. Gene expression data revealed that BdMAPK cascade kinases were rapidly regulated by stresses and phytohormones. Importantly, we have constructed a regulation network based on co-expression patterns of the expression profiles upon multiple stresses performed in this study.

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Determination of Rab5 Activity in the Cell by Effector Pull-Down Assay

Rab5 targets to early endosomes and is a master regulator of early endosome fusion and endocytosis in all eukaryotic cells. Like other GTPases, Rab5 functions as a molecular switch by alternating between GTP-bound and GDP-bound forms, with the former being biologically active via interactions with multiple effector proteins. Thus the Rab5-GTP level in the cell reflects Rab5 activity in promoting endosome fusion and endocytosis and is indicative of cellular endocytic activity. In this chapter, we describe a Rab5 activity assay by using GST fusion proteins with the Rab5 effectors such as Rabaptin-5, Rabenosyn-5, and EEA1 that specifically bind to GTP-bound Rab5. We compare the efficiencies of the three GST fusion proteins in the pull-down of mammalian and fungal Rab5 proteins.
Elsa Ballini's insight:

In addition, they characterize two Rab5 homologs (MoRab5A and MoRab5B) from Magnaporthe
oryzae, a pathogenic fungus that infects plants and causes rice blast disease

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Brachypodium as an emerging model for cereal–pathogen interactions

Brachypodium as an emerging model for cereal–pathogen interactions | Rice Blast | Scoop.it
Abstract

Background Cereal diseases cause tens of billions of dollars of losses annually and have devastating humanitarian consequences in the developing world. Increased understanding of the molecular basis of cereal host–pathogen interactions should facilitate development of novel resistance strategies. However, achieving this in most cereals can be challenging due to large and complex genomes, long generation times and large plant size, as well as quarantine and intellectual property issues that may constrain the development and use of community resources. Brachypodium distachyon (brachypodium) with its small, diploid and sequenced genome, short generation time, high transformability and rapidly expanding community resources is emerging as a tractable cereal model.

Scope Recent research reviewed here has demonstrated that brachypodium is either susceptible or partially susceptible to many of the major cereal pathogens. Thus, the study of brachypodium–pathogen interactions appears to hold great potential to improve understanding of cereal disease resistance, and to guide approaches to enhance this resistance. This paper reviews brachypodium experimental pathosystems for the study of fungal, bacterial and viral cereal pathogens; the current status of the use of brachypodium for functional analysis of cereal disease resistance; and comparative genomic approaches undertaken using brachypodium to assist characterization of cereal resistance genes. Additionally, it explores future prospects for brachypodium as a model to study cereal–pathogen interactions.

Conclusions The study of brachypodium–pathogen interactions appears to be a productive strategy for understanding mechanisms of disease resistance in cereal species. Knowledge obtained from this model interaction has strong potential to be exploited for crop improvement.

Via Christophe Jacquet, Guogen Yang
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Colloque SFP 2015

Colloque SFP 2015 | Rice Blast | Scoop.it
Sessions thématiques

1. Taxonomie, diagnostic et détection des agents phytopathogènes

2. Interactions plante-pathogène et plante-symbiote : mécanismes, vection, génomique et réponse de la plante

3. Épidémiologie aux différentes échelles, génétique des populations et écologie évolutive du parasitisme et de la symbiose

4. Protection des plantes, résistance durable, nouvelles technologies et gestion des risques

Les sessions seront introduites par un conférencier invité.  Ont déjà donné leur accord :

    Dr Olivier LE GALL,

    Pr Saskia HOGENHOUT,

    Dr Dominique BLANCARD,

    Dr Pascal SIMONET,

    Pr Philippe LEPOIVRE,

Des sessions "posters" seront aussi organisées.

Enfin, le colloque propose également une session ouverte au grand public consacré aux métiers de la phytopathologie (enseignement, recherche privée, épidémio-surveillance, phytodiagnostic, conseil agricole, journalisme agricole).

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Magnaporthe Rab5 homologs show distinctfunctions in NGF-mediated neurite outgrowth and cell differentiation

Magnaporthe Rab5 homologs show distinctfunctions in NGF-mediated neurite outgrowth and cell differentiation | Rice Blast | Scoop.it
Nerve growth factor (NGF) binds to TrkA and forms a NGF/TrkA complex at the cell surface, which is then internalized into signaling endosomes and promotes neuronal survival and neurite outgrowth. The small GTPase Rab5 is reported to localize on the plasma membrane and early endosomes, regulating endosome fusion. It was reported that endogenous Rab5 function may need to be suppressed during NGF-induced neurite outgrowth and cell differentiation. Two Rab5 homologs (MoRab5A:MGG_06241 and MoRab5B:MGG_01185) were identified and characterized from the rice blast fungus Magnapothe oryzae, and MoRab5B was identified as the Rab5 ortholog promoting early endosomal fusion, while MoRab5A specialized to perform a non-redundant function in endosomal sorting. In this study, we examined whether MoRab5A and MoRab5B play different roles in NGF-induced neurite outgrowth and cell differentiation in PC12 cells (a rat pheochromocytoma cell line). Our data showed that MoRab5B is a negative regulator of NGF signaling and neurite outgrowth in PC12 cells, similar to human Rab5 (hRab5). MoRab5B:WT inhibits NGF signaling-dependent neurite outgrowth while the dominant-negative MoRab5B mutant (MoRab5B:DN) enhances NGF signaling and neurite outgrowth. In contrast, MoRab5A:WT and MoRab5A:DN both significantly promote NGF-induced neurite outgrowth, indicating that MoRab5B is more similar to hRab5 than MoRab5A in the regulation of NGF signal transduction.
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Rmg7, a New Gene for Resistance to Triticum Isolates of Pyricularia oryzae Identified in Tetraploid Wheat

Rmg7, a New Gene for Resistance to Triticum Isolates of Pyricularia oryzae Identified in Tetraploid Wheat | Rice Blast | Scoop.it
A single gene for resistance, designated Rmg7 (Resistance to Magnaporthe grisea 7), was identified in a tetraploid wheat accession, St24 (Triticum dicoccum, KU120), against Br48, a Triticum isolate of Pyricularia oryzae. Two other wheat accessions, St17 (T. dicoccum, KU112) and St25 (T. dicoccum, KU122), were also resistant against Br48 and showed a similar disease reaction pattern to St24. Crosses between these resistant accessions yielded no susceptible F2 seedlings, suggesting that St24, St17, and St25 carry the same resistance gene. Furthermore, a single avirulence gene corresponding to Rmg7 was detected in a segregation analysis of random F1 progenies between Br48 and MZ5-1-6, an Eleusine isolate virulent to St24 at a higher temperature. This avirulence gene was recognized not only by St24, but also by St17 and St25, thus supporting the preceding results indicating that all three accessions carry Rmg7. This resistance gene may have potential in future wheat breeding programs.
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Methionine Biosynthesis is Essential for Infection in the Rice Blast Fungus Magnaporthe oryzae

Methionine Biosynthesis is Essential for Infection in the Rice Blast Fungus  Magnaporthe oryzae | Rice Blast | Scoop.it
Methionine is a sulfur amino acid standing at the crossroads of several biosynthetic pathways. In fungi, the last step of methionine biosynthesis is catalyzed by a cobalamine-independent methionine synthase (Met6, EC 2.1.1.14). In the present work, we studied the role of Met6 in the infection process of the rice blast fungus, Magnaporthe oryzae. To this end MET6 null mutants were obtained by targeted gene replacement. On minimum medium, MET6 null mutants were auxotrophic for methionine. Even when grown in presence of excess methionine, these mutants displayed developmental defects, such as reduced mycelium pigmentation, aerial hypha formation and sporulation. They also displayed characteristic metabolic signatures such as increased levels of cysteine, cystathionine, homocysteine, S-adenosylmethionine, S-adenosylhomocysteine while methionine and glutathione levels remained unchanged. These metabolic perturbations were associated with the over-expression of MgCBS1 involved in the reversed transsulfuration pathway that metabolizes homocysteine into cysteine and MgSAM1 and MgSAHH1 involved in the methyl cycle. This suggests a physiological adaptation of M. oryzae to metabolic defects induced by the loss of Met6, in particular an increase in homocysteine levels. Pathogenicity assays showed that MET6 null mutants were non-pathogenic on both barley and rice leaves. These mutants were defective in appressorium-mediated penetration and invasive infectious growth. These pathogenicity defects were rescued by addition of exogenous methionine and S-methylmethionine. These results show that M. oryzae cannot assimilate sufficient methionine from plant tissues and must synthesize this amino acid de novo to fulfill its sulfur amino acid requirement during infection.
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Pseudo-backcrossing design for rapidly pyramiding multiple traits into a preferential rice variety

Four resistance donors with five target genes (Sub1A-C, xa5, Xa21, TPS and SSIIa) and three QTLs (qBph3, qBL1 and qBL11) were backcrossed individually using markers into the pseudo-recurrent parent ‘PinK3’ via one cycle of backcrossing followed by two cycles of pseudo-backcrossing and three selfings with rigorous foreground marker-assisted selection. In total, 29 pseudo-backcross inbred lines (BILs) were developed. Genome composition was surveyed using 61 simple sequence repeats (SSRs), 35 of which were located on six carrier chromosomes, with the remainder located on six non-carrier chromosomes. The recurrent genome content (%RGC) and donor genome content (%DGC), which were based on the physical positions of BC1F2, ranged from 69.99 to 88.98% and 11.02 to 30.01%, respectively. For the pseudo-BC3F3BILs, the %RGC and %DGC ranged from 74.50 to 81.30% and 18.70 to 25.50%, respectively. These results indicated that without direct background selection, no further increases in %RGC were obtained during pseudo-backcrossing, whereas rigorous foreground marker-assisted selection tended to reduce linkage drag during pseudo-backcrossing. The evaluation of new traits in selected pseudo-BC3F3BILs indicated significant improvements in resistance to BB, BL, BPH and Sub compared with PinK3, as well as significant improvements in grain yield (21-68%) over the donors, although yield was 7-26% lower than in ‘PinK3’. All pyramided lines were aromatic and exhibited improved starch profiles, rendering them suitable for industrial food applications.
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Current advance methods for the identification of blast resistance genes in rice

Current advance methods for the identification of blast resistance genes in rice | Rice Blast | Scoop.it
Rice blast caused by Magnaporthe oryzae is one of the most devastating diseases of rice around the world and crop losses due to blast are considerably high. Many blast resistant rice varieties have been developed by classical plant breeding and adopted by farmers in various rice-growing countries. However, the variability in the pathogenicity of the blast fungus according to environment made blast disease a major concern for farmers, which remains a threat to the rice industry. With the utilization of molecular techniques, plant breeders have improved rice production systems and minimized yield losses. In this article, we have summarized the current advanced molecular techniques used for controlling blast disease. With the advent of new technologies like marker-assisted selection, molecular mapping, map-based cloning, marker-assisted backcrossing and allele mining, breeders have identified more than 100 Pi loci and 350 QTL in rice genome responsible for blast disease. These Pi genes and QTLs can be introgressed into a blast-susceptible cultivar through marker-assisted backcross breeding. These molecular techniques provide timesaving, environment friendly and labour-cost-saving ways to control blast disease. The knowledge of host–plant interactions in the frame of blast disease will lead to develop resistant varieties in the future.
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Global Genome and Transcriptome Analyses of Magnaporthe oryzae Epidemic Isolate 98-06 Uncover Novel Effectors and Pathogenicity-Related Genes, Revealing Gene Gain and Lose Dynamics in Genome Evol...

Global Genome and Transcriptome Analyses of  Magnaporthe oryzae  Epidemic Isolate 98-06 Uncover Novel Effectors and Pathogenicity-Related Genes, Revealing Gene Gain and Lose Dynamics in Genome Evol... | Rice Blast | Scoop.it
Genetic variations in pathogens, such as the causal agent of rice blast Magnaporthe oryzae, often lead to circumvention of disease-resistance cultivars. Previous genome-wide analyses of model organisms suggest that pathogen effectors are also rapidly evolving, especially in regions with high genome plasticity. However, genetic variations among different isolates remain largely unknown in M. oryzae, particularly at the genome and transcriptome levels. In this study, we provided a systematic genomic and interaction transcriptome profile for a dominant rice blast field isolate, resulting in identification of 134 candidate effectors. Two effectors, Iug6 and Iug9, and one pathogenicity-related (PaR) gene product, Iug18, were subjected to functional characterization. We found that Iug6 and Iug9 are located in the biotrophic interfacial complex (BIC) and their overexpression leads to suppression of defense-related gene expression in rice, while Iug18 appears to be a novel PaR protein. Our studies support the hypothesis that isolate-unique genes may serve as a source of genetic variability in the M. oryzae population encountering different environments. Our studies also facilitate further understanding of effectors and genomic variations in pathogenicity of M. oryzae.
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Phytochemical screening and antimicrobial activities of the constituents isolated from Koelreuteria paniculata leaves

Methanolic extract of Golden rain leaves was fractionated by column chromatography on silica gel and 18 fractions were obtained. Antimicrobial activities of fractions were investigated against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa as quality control bacteria and fungus Pyricularia grisea which causes Blast disease in rice. Fractions showed more antibacterial activity at 0.04 g/mL concentration only on B. subtilis and S. aureus as gram positive bacteria. Also, three fractions indicated excellent antifungal effect on fungus P. grisea. Moreover, in the present study, fractions that showed very good effect on microorganisms were used for gas chromatography-mass spectrometry analysis to identify different phytochemicals.
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Population structure, pathogenicity and mating type distribution of Magnaporthe oryzae isolates from East Africa

Population structure, pathogenicity and mating type distribution of Magnaporthe oryzae isolates from East Africa | Rice Blast | Scoop.it
Rice blast, caused by Magnaporthe oryzae, is one of the emergent threats to rice production in East Africa (EA), where yet little is known about the population genetics and pathogenicity of this pathogen. We investigated the genetic diversity and mating type distribution of 88 isolates of Magnaporthe oryzae from EA and representative isolates from West Africa (WA) and the Philippines (Asia) using amplified fragment length polymorphism (AFLP) markers and mating type specific primer sets. In addition, the aggressiveness of each isolate was evaluated by inoculating on the susceptible Oryza sativa indica cultivar Co39, scoring the disease severity and calculating the disease progress. Hierarchical analysis of molecular variance revealed a low level of genetic differentiation at two levels (FST 0.12 and FCT 0.11). No evidence of population structure was found among the 65 isolates from EA, and gene flow among EA populations was high. Moreover, pair wise population differentiation (GST) in EA populations ranged from 0.03-0.04, suggesting that >96% of genetic variation is derived from within populations. The populations from Asia and WA were however moderately differentiated from EA ones. The spatial analysis of principal coordinates (PCoA) and STRUCTURE revealed overlapping between individual M. oryzae isolates from EA, with limited distinctness according to the geographic origin. All the populations were clonal, given the positive and significant index of association (IA) and standardized index of association (rd), which indicates a significant (P<0.001) departure from panmixia (IA and rd =0). Both mating types (Mat1-1 and Mat1-2) were detected. However, MAT 1-1 was more prevalent than MAT 1-2. Pathogenicity analysis revealed variability in aggressiveness, suggesting a potential existence of different races. Our data suggest that M. oryzae populations from EA could be either distributed as a single genetic population or that gene flow is exerting a significant influence, effectively swamping the action of selection. This is the first study on genetic differentiation of rice infecting M. oryzae strains from EA, and may guide further studies on the pathogen as well as resistance breeding efforts.
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Fungal biology in the post-genomic era

In this review I give a personal perspective of how fungal biology has changed since I started my Ph. D. in 1963. At that time we were working in the shadow of the birth of molecular biology as an autonomous and reductionistic discipline, embodied in Crick’s central dogma. This first period was methodologically characterised by the fact that we knew what genes were, but we could not access them directly. This radically changed in the 70s-80s when gene cloning, reverse genetics and DNA sequencing become possible. The “next generation” sequencing techniques have produced a further qualitative revolutionary change. The ready access to genomes and transcriptomes of any microbial organism allows old questions to be asked in a radically different way and new questions to be approached. I provide examples chosen somewhat arbitrarily to illustrate some of these changes, from applied aspects to fundamental problems such as the origin of fungal specific genes, the evolutionary history of genes clusters and the realisation of the pervasiveness of horizontal transmission. Finally, I address how the ready availability of genomes and transcriptomes could change the status of model organisms.

Via Francis Martin, Enric Gracia
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Steve Marek's curator insight, April 13, 11:12 AM

Nice overview of recent advances with historical contexts

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Characterization of rice blast resistance genes in rice germplasm with monogenic lines and pathogenicity assays

Characterization of rice blast resistance genes in rice germplasm with monogenic lines and pathogenicity assays | Rice Blast | Scoop.it

We provided information on blast resistance gene deployment.
Pi9 and Pita2 are effective blast resistance genes in the USA.
Ten out of 14 commonly found races of Magnaporthe oryzae were highly virulent.
Eight rice germplasm have more than two blast resistance genes.

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An S-(Hydroxymethyl)Glutathione Dehydrogenase Is Involved in Conidiation and Full Virulence in the Rice Blast Fungus Magnaporthe oryzae

An S-(Hydroxymethyl)Glutathione Dehydrogenase Is Involved in Conidiation and Full Virulence in the Rice Blast Fungus  Magnaporthe oryzae | Rice Blast | Scoop.it

Magnaporthe oryzae is a hemibiotrophic fungal pathogen that causes rice blast disease. A compatible interaction requires overcoming plant defense responses to initiate colonization during the early infection process.


Via Yanping Tian
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Activation of the signaling mucin MoMsb2 and its functional relationship with Cbp1 in Magnaporthe oryzae

Activation of the signaling mucin MoMsb2 and its functional relationship with Cbp1 in Magnaporthe oryzae | Rice Blast | Scoop.it
Various surface signals are recognized by Magnaporthe oryzae to activate the Pmk1 MAP kinase that is essential for appressorium formation and invasive growth. One of upstream sensors of the Pmk1 pathway is the MoMsb2 signaling mucin. However, the activation of MoMsb2 and its relationship with other sensors is not clear. In this study, we showed that the cleavage and transmembrane domains are essential for MoMsb2 functions. Cleavage of MoMsb2 was further confirmed by western blot analysis and five putative cleavage sites were functionally characterized. Expression of the extracellular region alone partially rescued the defects of Momsb2 in appressorium formation and virulence. The cytoplasmic region of MoMsb2, although dispensable for appressorium formation, was more important for penetration and invasive growth. Interestingly, the Momsb2 cbp1 double mutant deleted of both mucin genes was blocked in Pmk1 activation. It failed to form appressoria on artificial surfaces and was non-pathogenic. In addition, we showed that MoMsb2 interacts with Ras2 but not with MoCdc42 in co-IP assays. Overall, results from this study indicated that the extracellular and cytoplasmic regions of MoMsb2 have distinct functions in appressorium formation, penetration, and invasive growth, and MoMsb2 has overlapping functions with Cbp1 in recognizing environmental signals for Pmk1 activation.
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Efficacy of Selected Plant Extracts against Pyricularia grisea, Causal Agent of Rice Blast Disease

Efficacy of Selected Plant Extracts against Pyricularia grisea, Causal Agent of Rice Blast Disease | Rice Blast | Scoop.it
Rice blast disease, caused by a seed-borne fungus Pyricularia grisea, is an important and serious disease of rice (Oryza sativa L.) worldwide. The disease has been reported to cause yield losses of up to 40% in Tanzania. Studies were conducted to determine the effect of aqueous extracts of Aloe vera, Allium sativum, Annona muricata, Azadirachta indica, Bidens pilosa, Camellia sinensis, Chrysanthemum coccineum, processed Coffee arabica, Datura stramonium, Nicotiana tabacum and Zingiber officinalis for control of rice blast disease (Pyricularia grisea) in-vitro and in-vivo. The results indicate that processed C. arabica at 10% and 25% (v/v) had the highest (81.12%) and (89.40%) inhibitory effect, respectively, against P. grisea. Aqueous extract from N. tabacum at 10% concentration ranked third (80.35%) in inhibiting P. grisea. These were followed by extracts from 25% A. vera (79.45%) and 25% C. coccineum flower (78.83%). The results also indicate that, extracts from A. indica, A. vera, A. sativum, C. arabica, D. stramonium, C. sinensis, Z. officinalis and N. tabacum did not have any phytotoxic effect on seed germination, shoot height, root length, dry weight, seedling growth and seedling vigour index. These plant extracts can thus be used for rice seed treatment to manage rice blast disease.
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