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Scientific articles on rice blast and wheat blast 20 new articles each month !
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Molecular Characterization and virulence pattern studies of rice (Oryza Sativa) blast (Magnaporthe Oryzae) disease

The population genetics of M.oryza were analyzed in three locations i.e. Mandya (Southern dry zone), Ponnampet (Hilly zone) and Bangalore for (pathogenicity test). Disease was evaluated for their pathogenic virulence and genetic characterization using Avr gene specific markers. Isolates were classified into three groups based on pathogenicity viz., seven-severely pathogenic (isolates), 11 moderately pathogenic and three mildly pathogenic isolates. Study revealed, among 21 isolates collected, Avr genes were found in 18 isolates for gene AvrPita, 15 for Avr-Pitz, four for Avr- Co-39, 12 in Avr-Pia and 8 in Avr-Pik gene. The isolates of Mandya were highly variable than Ponnampet (through cluster analysis). This study helps in understanding the response of different rice accessions to blast in different locations, the distribution and contribution of Avr genes for host plant resistance.

• Majority of isolates were grouped under moderate virulence though pathogenisity test and molecular analysis.
• The suitable temperature for the cultural growth of all the isolates was 28±2°C. Least number of isolates were having Avr-Co-39genes.
• Through the virulence pattern and Avr gene distribution studies in leading cultivars and varieties, there is a scope in altering the pathogenicity which may pave a way for disease management.

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Bioactive Compounds Produced by Streptomyces sp. Isolate UPMRS4 and Antifungal Activity against Pyricularia oryzae

A Streptomyces isolate having antifungal activity against Pyricularia oryzae, the causal agent of rice blast disease, was isolated from soil collected in rice fields of Tanjung Karang Selangor, peninsula Malaysia.The aim of the study was to determine the antifungal activity of Streptomyces sp. isolate UPMRS4 extracts against P. oryzae and to identify bioactive antifungal compounds produced by UPMRS4. Various solvents were used for extraction of antifungal compounds and well diffusion method was used to determine the antifungal activity of the extracts. The ethyl acetate extract demonstrated the highest activity against mycelial growth of P. oryzae, with an effective inhibitory concentration (EIC) of 1.562 μg/ml significantly higher compared to that of chloroform, diethyl ether, methanol, acetone, ethanol and water. Based on GC-MS and LC-MS/MSanalyses,compounds with antifungal activity were detected such as (Pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); Pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(phenylmethyl); ergotamine; amicomacin; fungichromin; rapamycin and N-Acetyl-D, L-phenylalanine. These compounds had good general antifungal activity and might have potential future agricultural applications.
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Antifungal Activity of Eucalyptus Oil against Rice Blast Fungi and the Possible Mechanism of Gene Expression Pattern

Eucalyptus oil possesses a wide spectrum of biological activity, including anti-microbial, fungicidal, herbicidal, acaricidal and nematicidal properties. We studied anti-fungal activities of the leaf oil extracted from Eucalyptus. grandis × E. urophylla. Eleven plant pathogenic fungi were tested based on the mycelium growth rates with negative control. The results showed that Eucalyptus oil has broad-spectrum inhibitory effects toward these fungi. Remarkable morphological and structural alterations of hypha have been observed for Magnaporthe grisea after the treatment. The mRNA genome array of M. grisea was used to detect genes that were differentially expressed in the test strains treated by the Eucalyptus oil than the normal strains. The results showed 1919 genes were significantly affected, among which 1109 were down-regulated and 810 were up-regulated (p 2). According to gene ontology annotation analysis, these differentially expressed genes may cause abnormal structures and physiological function disorders, which may reduce the fungus growth. These results show the oil has potential for use in the biological control of plant disease as a green biopesticide.
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Host specialization of the blast fungus Magnaporthe oryzae is associated with dynamic gain and loss of genes linked to transposable elements

Host specialization of the blast fungus Magnaporthe oryzae is associated with dynamic gain and loss of genes linked to transposable elements | Rice Blast | Scoop.it

Fig. 5 Highly polymorphic in the effector genes between and within the host-specific subgroups of M. oryzae. a The percentage of genes showing loss, outlier values of dN/dS when dN/dS was included or excluded for each functional category. The black and gray bars indicate the percentage of genes showing loss or outlier values of dN/dS and the others, respectively. These percentages were calculated when we used 70-15 strain genome as the reference. b Distribution of presence and absence of genes encoding the known effectors in M. oryzae and M. grisea. Heat map shows breadth coverage of genes. The blue and yellow panels indicate absence and presence polymorphisms, respectively. The tree indicates the relationship among the tested pathogens based on Fig. 1b


Background
Magnaporthe oryzae (anamorph Pyricularia oryzae) is the causal agent of blast disease of Poaceae crops and their wild relatives. To understand the genetic mechanisms that drive host specialization of M. oryzae, we carried out whole genome resequencing of four M. oryzae isolates from rice (Oryza sativa), one from foxtail millet (Setaria italica), three from wild foxtail millet S. viridis, and one isolate each from finger millet (Eleusine coracana), wheat (Triticum aestivum) and oat (Avena sativa), in addition to an isolate of a sister species M. grisea, that infects the wild grass Digitaria sanguinalis.

Results
Whole genome sequence comparison confirmed that M. oryzae Oryza and Setaria isolates form a monophyletic and close to another monophyletic group consisting of isolates from Triticum and Avena. This supports previous phylogenetic analysis based on a small number of genes and molecular markers. When comparing the host specific subgroups, 1.2–3.5 % of genes showed presence/absence polymorphisms and 0–6.5 % showed an excess of non-synonymous substitutions. Most of these genes encoded proteins whose functional domains are present in multiple copies in each genome. Therefore, the deleterious effects of these mutations could potentially be compensated by functional redundancy. Unlike the accumulation of nonsynonymous nucleotide substitutions, gene loss appeared to be independent of divergence time. Interestingly, the loss and gain of genes in pathogens from the Oryza and Setaria infecting lineages occurred more frequently when compared to those infecting Triticum and Avena even though the genetic distance between Oryza and Setaria lineages was smaller than that between Triticum and Avena lineages. In addition, genes showing gain/loss and nucleotide polymorphisms are linked to transposable elements highlighting the relationship between genome position and gene evolution in this pathogen species.

Conclusion
Our comparative genomics analyses of host-specific M. oryzae isolates revealed gain and loss of genes as a major evolutionary mechanism driving specialization to Oryza and Setaria. Transposable elements appear to facilitate gene evolution possibly by enhancing chromosomal rearrangements and other forms of genetic variation.


Via Steve Marek, Thorsten Langner
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OryzaGenome: Genome Diversity Database of Wild Oryza Species

OryzaGenome: Genome Diversity Database of Wild Oryza Species | Rice Blast | Scoop.it
The species in the genus Oryza, encompassing nine genome types and 23 species, are a rich genetic resource and may have applications in deeper genomic analyses aiming to understand the evolution of plant genomes. With the advancement of next-generation sequencing (NGS) technology, a flood of Oryza species reference genomes and genomic variation information has become available in recent years. This genomic information, combined with the comprehensive phenotypic information that we are accumulating in our Oryzabase, can serve as an excellent genotype–phenotype association resource for analyzing rice functional and structural evolution, and the associated diversity of the Oryza genus. Here we integrate our previous and future phenotypic/habitat information and newly determined genotype information into a united repository, named OryzaGenome, providing the variant information with hyperlinks to Oryzabase. The current version of OryzaGenome includes genotype information of 446 O. rufipogon accessions derived by imputation and of 17 accessions derived by imputation-free deep sequencing. Two variant viewers are implemented: SNP Viewer as a conventional genome browser interface and Variant Table as a text-based browser for precise inspection of each variant one by one. Portable VCF (variant call format) file or tab-delimited file download is also available. Following these SNP (single nucleotide polymorphism) data, reference pseudomolecules/scaffolds/contigs and genome-wide variation information for almost all of the closely and distantly related wild Oryza species from the NIG Wild Rice Collection will be available in future releases.
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Biological preparation of chitosan nanoparticles and its in vitro antifungal efficacy against some phytopathogenic fungi

Biological preparation of chitosan nanoparticles and its in vitro antifungal efficacy against some phytopathogenic fungi | Rice Blast | Scoop.it
The aim of the present study was to prepare Chitosan nanoparticles through biological method with high antifungal activities. Chitosan nanoparticles were prepared by the addition of anionic proteins isolated from Penicillium oxalicum culture to chitosan solutions. The formation of chitosan nanoparticles was preliminary confirmed by UV-Visible spectrophotometric analysis. The physico-chemical properties of the chitosan nanoparticles were determined by size and zeta potential analysis, FTIR analysis, HRTEM and XRD pattern. The chitosan nanoparticles were evaluated for its potential to inhibit the growth of phytopathogens viz., Pyricularia grisea, Alternaria solani, Fusarium oxysporum. It is evident from our results that chitosan nanoparticles inhibit the growth of phytopathogens tested. Chitosan nanoparticle treated chickpea seeds showed positive morphological effects such as enhanced germination %, seed vigor index and vegetative biomass of seedlings. All these results indicates that chitosan nanoparticle can be used further under field condition to protect various crops from the devastating fungal pathogens as well as growth promoters.
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Wheat blast disease caused by Pyricularia graminis-tritici sp. nov.- comments

See here all the discussion and comments about the recent paper "Wheat blast disease caused by Pyricularia graminis-tritici sp. nov."
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The Role of Rice Leaf Surface Properties in the Appressorium Formation

The organism Magnaporthe oryzae is one of the leading causes of rice blast fungus, a disease that greatly affects rice crop yields. Given that rice supplies around twenty percent of the world’s total calories consumed, it is important to investigate factors that affect its harmful progression.

The goal of this study is to determine the effects of surface properties in the attachment of M. oryzae to the rice leaf, and how these properties affect appressorium formation. Properties investigated include stiffness, thickness, surface roughness, and wettability. For repeatability, a silicone-based elastomer with which these variables could be controlled was fabricated.

Tests were first carried out to mimic the surface roughness of the rice leaf. Surface roughness for both rice leaf surfaces and elastomer substrates were measured using a goniometer. Data from these test were compiled with Excel. Following these initial tests, substrates of varying thicknesses were created to test appressorium formation.
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Blast Resistant Early Maturing Rice ‘Jungmo1024’ with High Temperature Tolerance during Grain Filling Stage

‘Jungmo1024’ is a blast resistant early maturing rice cultivar with high temperature tolerance during grain filling stage. ‘Jungmo1024’ was derived from a sodium azide treatment on ‘Suweon472’, a high yielding japonica elite line which was latterly registered as ‘Namil’. Comparison with the agronomical traits of ‘Namil’, ‘Jungmo1024’ was uniquely characterized as the induced gained function due to the reduced culm length, increased tiller number, strong blast resistance and especially high temperature tolerance during grain filling stage. The high temperature tolerance of ‘Jungmo1024’ was supported by two years experiments by comparing the head rice ratio produced in ordinary paddy field and green house condition. The heading date of ‘Jungmo1024’ was July 29 in central plain area, which was 9 days earlier than that of ‘Hwaseong’. The milled rice yield performance of ‘Jungmo1024’ was about 4.98 MT/ha in local adaptability test for three years. ‘Jungmo1024’ had 69 cm in culm length, which was 15 cm shorter than that of ‘Hwaseong’, 20 cm in panicle length, 16 in tiller number, and 22.3g in 1,000 grain-weight of brown rice. ‘Jungmo1024’ exhibited strong rice blast resistance, but do not have any clear resistance gene sources against bacterial blight, viral diseases and insect fests. ‘Jungmo1024’, nevertheless, would be a useful rice cultivar could be used as a donor line for the breeding programs for developing southern plane adaptable early maturing rice cultivars with enhanced rice blast resistance, lodging tolerance, and especially high temperature tolerance during grain filling stage.
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Allele-specific marker-based assessment revealed that the rice blast resistance genes Pi2

Allele-specific marker-based assessment revealed that the rice blast resistance genes Pi2 | Rice Blast | Scoop.it
In this work, we developed two new markers, named Pi9-Pro and Pi2-LRR respectively, targeting the unique polymorphisms of the resistant and susceptible alleles of Pi2 and of Pi9. The InDel marker Pi9-Pro differentiates three different genotypes corresponding to the Pi2/Piz-t, Pi9 and non-Pi2/Piz-t/Pi9 alleles, and the CAPS marker Pi2-LRR differentiates the Pi2 allele from the non-Pi2 allele. Based on the two newly developed markers and two available markers Pi2SNP and Pi9SNP, the presence of Pi2 and Pi9 was assessed in a set of 434 rice accessions consisting of 377 Chinese indica cultivars/breeding materials and 57 Chinese japonica cultivars/breeding materials. Of the 434 accessions tested, while one indica restorer line Huazhan was identified harboring the Pi2 resistance allele, no other rice line was identified harboring the Pi2 or Pi9 resistance alleles.
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Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species | Rice Blast | Scoop.it
One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants.
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bioRxiv: Wheat blast disease caused by Pyricularia graminis-tritici sp. nov. (2016)

bioRxiv: Wheat blast disease caused by Pyricularia graminis-tritici sp. nov. (2016) | Rice Blast | Scoop.it

Pyricularia oryzae is a species complex that causes blast disease on more than 50 species of poaceous plants. Pyricularia oryzae has a worldwide distribution as a rice (Oryza) pathogen and in the last century emerged as an important wheat (Triticum) pathogen in southern Brazil. Presently, P. oryzae pathotype Oryza is considered the rice blast pathogen, whereas P. oryzae pathotype Triticum is the wheat blast pathogen. In this study we investigated whether the Oryza and Triticum pathotypes of P. oryzae were distinct at the species level. We also describe a new Pyricularia species causing blast on several other poaceous hosts in Brazil, including wheat. We conducted phylogenetic analyses using 10 housekeeping loci from an extensive sample (N = 128) of sympatric populations of P. oryzae adapted to rice, wheat and other poaceous hosts found in or near wheat fields. The Bayesian phylogenetic analysis grouped the isolates into two major monophyletic clusters (I and II) with high Bayesian probabilities (P = 0.99). Cluster I contained isolates obtained from wheat as well as other Poaceae hosts (P = 0.98). Cluster II was divided into three host-associated clades (Clades 1, 2 and 3; P > 0.75). Clade 1 contained isolates obtained from wheat and other poaceous hosts, Clade 2 contained exclusively wheat-derived isolates, and Clade 3 comprised isolates associated only with rice. Our interpretation was that cluster I and cluster II correspond to two distinct species: Pyricularia graminis-tritici sp. nov. (Pgt), newly described in this study, and Pyricularia oryzae (Po). The host-associated clades found in P. oryzae Cluster II correspond to P. oryzae pathotype Triticum (PoT; Clades 1 and 2), and P. oryzae pathotype Oryza (PoO; Clade 3). No morphological or cultural differences were observed among these species, but a distinctive pathogenicity spectrum was observed. Pgt and PoT were pathogenic and highly aggressive on Triticum aestivum (wheat), Hordeum vulgare (barley), Urochloa brizantha (signal grass) and Avena sativa (oats). PoO was highly virulent on the original rice host (Oryza sativa), and also on wheat, barley, and oats, but not on signal grass. We concluded that blast disease on wheat and its associated Poaceae hosts in Brazil is caused by multiple Pyricularia species: the newly described Pyricularia graminis-tritici sp. nov., and the known P. oryzae pathotypes Triticum and Oryza. To our knowledge, P. graminis-tritici sp. nov. is still restricted to Brazil, but obviously represents a serious threat to wheat cultivation globally.


Via Kamoun Lab @ TSL
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Magnaporthe oryzae Effector AVR-Pii Helps to Establish Compatibility by Inhibition of the Rice NADP-Malic Enzyme Resulting in Disruption of Oxidative Burst and Host Innate Immunity

Magnaporthe oryzae Effector AVR-Pii Helps to Establish Compatibility by Inhibition of the Rice NADP-Malic Enzyme Resulting in Disruption of Oxidative Burst and Host Innate Immunity | Rice Blast | Scoop.it
Plant disease resistance occurs as a hypersensitive response (HR) at the site of attempted pathogen invasion. This specific event is initiated in response to recognition of pathogen-associated molecular pattern (PAMP) and subsequent PAMP-triggered immunity (PTI) and effector-triggered immunity (ETI). Both PTI and ETI mechanisms are tightly connected with reactive oxygen species (ROS) production and disease resistance that involves distinct biphasic ROS production as one of its pivotal plant immune responses. This unique oxidative burst is strongly dependent on the resistant cultivars because a monophasic ROS burst is a hallmark of the susceptible cultivars. However, the cause of the differential ROS burst remains unknown. In the study here, we revealed the plausible underlying mechanism of the differential ROS burst through functional understanding of the Magnaporthe oryzae (M. oryzae) AVR effector, AVR-Pii. We performed yeast two-hybrid (Y2H) screening using AVRPii as bait and isolated rice NADP-malic enzyme2 (Os-NADP-ME2) as the rice target protein. To our surprise, deletion of the rice Os-NADP-ME2 gene in a resistant rice cultivar disrupted innate immunity against the rice blast fungus. Malic enzyme activity and inhibition studies demonstrated that AVR-Pii proteins specifically inhibit in vitro NADP-ME activity. Overall, we demonstrate that rice blast fungus, M. oryzae attenuates the host ROS burst via AVR-Pii-mediated inhibition of Os-NADP-ME2, which is indispensable in ROS metabolism for the innate immunity of rice. This characterization of the regulation of the host oxidative burst will help to elucidate how the products of AVR genes function associated with virulence of the pathogen.
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Fungi associated with foliar diseases of wild and cultivated rice (Oryza spp.) in northern Queensland

Fungi associated with foliar diseases of wild and cultivated rice (Oryza spp.) in northern Queensland | Rice Blast | Scoop.it

During surveys of wild and cultivated rice in northern Queensland in 2014 and 2015, 92 fungal isolates were obtained from plants that were afflicted by foliar diseases, including the rice blast pathogen, Pyricularia oryzae.To remove uncertainty about the identity of the host plants from which the fungi were isolated, a DNA barcoding strategy was developed using regions of the chloroplast genome. Pathogenicity tests using wild rice isolates of P. oryzae indicated that many local rice varieties are susceptible to infection.

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A Genetic Screen Identifies a Requirement for Cysteine-Rich–Receptor-Like Kinases in Rice NH1 (OsNPR1)-Mediated Immunity

A Genetic Screen Identifies a Requirement for Cysteine-Rich–Receptor-Like Kinases in Rice NH1 (OsNPR1)-Mediated Immunity | Rice Blast | Scoop.it
Abstract

Systemic acquired resistance, mediated by the Arabidopsis NPR1 gene and the rice NH1 gene, confers broad-spectrum immunity to diverse pathogens. NPR1 and NH1 interact with TGA transcription factors to activate downstream defense genes. Despite the importance of this defense response, the signaling components downstream of NPR1/NH1 and TGA proteins are poorly defined. Here we report the identification of a rice mutant, snim1, which suppresses NH1-mediated immunity and demonstrate that two genes encoding previously uncharacterized cysteine-rich-receptor-like kinases (CRK6 and CRK10), complement the snim1 mutant phenotype. Silencing of CRK6 and CRK10 genes individually in the parental genetic background recreates the snim1 phenotype. We identified a rice mutant in the Kitaake genetic background with a frameshift mutation in crk10; this mutant also displays a compromised immune response highlighting the important role of crk10. We also show that elevated levels of NH1 expression lead to enhanced CRK10 expression and that the rice TGA2.1 protein binds to the CRK10 promoter. These experiments demonstrate a requirement for CRKs in NH1-mediated immunity and establish a molecular link between NH1 and induction of CRK10 expression.
Author Summary

To survive, plants and animals must resist microbial infection. Plants employ an immune response called systemic acquired resistance that confers long-lasting resistance to a broad-spectrum of pathogens. Researchers have previously identified two key proteins (NPR1/NH1 and TGA) that control this immune response. Despite these advances, there remain many gaps in our knowledge and understanding of this important immune response. We have identified a new gene (CRK10) required for this immune response; without it, plants are more susceptible to infection. These findings advance basic knowledge of systemic acquired resistance and open the door to a new avenue of research on this exciting and important resistance mechanism.

Via Christophe Jacquet
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Phosphodiesterase MoPdeH targets MoMck1 of the conserved mitogen-activated protein (MAP) kinase signalling pathway to regulate cell wall integrity in rice blast fungus Magnaporthe oryzae

Phosphodiesterase MoPdeH targets MoMck1 of the conserved mitogen-activated protein (MAP) kinase signalling pathway to regulate cell wall integrity in rice blast fungus Magnaporthe oryzae | Rice Blast | Scoop.it
In the rice blast fungus Magnaporthe oryzae, the high-affinity cyclic adenosine monophosphate (cAMP) phosphodiesterase MoPdeH is important not only for cAMP signalling and pathogenicity, but also for cell wall integrity (CWI) maintenance through an unknown mechanism. By utilizing affinity purification, we found that MoPdeH interacts with MoMck1, one of the components of the mitogen-activated protein (MAP) kinase cascade that regulates CWI. Overexpression of MoMCK1 suppressed defects in autolysis and pathogenicity of the ΔMopdeH mutant, although partially, suggesting that MoPdeH plays a critical role in CWI maintenance mediated by the MAP kinase pathway. We found that MoMck1 and two other MAP kinase cascade components, MoMkk1 and MoMps1, modulate intracellular cAMP levels by regulating the expression of MoPDEH through a feedback loop. In addition, disruption of MoMKK1 resulted in less aerial hyphal formation, defective asexual development and attenuated pathogenicity. Moreover, MoMkk1 plays a role in the response to osmotic stress via regulation of MoOsm1 phosphorylation levels, whereas endoplasmic reticulum (ER) stress enhances MoMps1 phosphorylation and loss of the MAP kinase cascade component affects the unfolded protein response (UPR) pathway. Taken together, our findings demonstrate that MoPdeH functions upstream of the MoMck1–MoMkk1–MoMps1 MAP kinase pathway to regulate CWI, and that MoPdeH also mediates crosstalk between the cAMP signalling pathway, the osmotic sensing high osmolarity glycerol (HOG) pathway and the dithiothreitol (DTT)-induced UPR pathway in M. oryzae.
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Population Genetics in R Hackathon
Open Call for Participation

Do you develop population genetics methods or algorithms in R? Are you a researcher wrestling with analyzing population genetics data in R? Have you run into difficulties with passing data or metadata from one R package to another? Have you run into problems with large datasets? Have you found documentation on building workflows from packages for population genetics analysis difficult to come by? Do you have expertise and ideas to share and energy to spend on overcoming these challenges? Do you enjoy collaborating with like-minded others to do so? If you answered some (or all) of these questions with yes, then the following event may be for you.

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Isolation, identification and in vitro evaluation of bacillus spp. in control of magnaporthe oryzae comparing evaluation methods

Environmentally friendly technologies, such as the use of bacteria (e.g. Bacillus spp.) to control fungal diseases of rice (Oryza sativa L.), represent a promising alternative for the sustainability of agricultural ecosystems. The present work aimed to isolate, identify, and evaluate (in vitro) various Bacillus spp. from the rice phylloplane for their potential to control the rice fungus Magnaporthe oryzae. Samples were taken from the phylloplane of healthy young rice plants growing in commercial fields in ten municipalities of Maranhão (Brazil), and Bacillus spp. were subsequently isolated and molecularly identified. Both experiments utilized a randomized design, and data were submitted to analysis of variance as well as means comparison by the Tukey test. Twelve bacterial isolates were obtained and identified. Using a control isolate (B25), four in vitro M. oryzae-inhibition methods were compared, with the ‘circle’ method ultimately providing the highest mycelium growth inhibition. The most promising experimental isolates for biological control were then identified as B. methylotrophicus isolates B41, B31, and B22, which achieved 90.41, 69.47, and 67.55% inhibition, respectively. This study demonstrates the potential of Maranhão Bacillus spp. isolates for use as biological fungal-control agents
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Fungal Genomics Challenges the Dogma of Name-Based Biosecurity

Fungal Genomics Challenges the Dogma of Name-Based Biosecurity | Rice Blast | Scoop.it

A paradigm shift is needed to overcome these serious shortcomings in biosecurity. Risk assessments should target the genes of pathogens rather than their names. Genomic research over the last decade has paved the way towards gene-based biosecurity. Detailed information about fungal genomes can help predict risks posed by undescribed pathogens through (i) prediction of lifestyle, e.g., biotrophic and saprotrophic fungi can be distinguished from nectrotrophic and hemibiotrophic fungi, and saprotrophic fungi can be distinguished from pathogens. In time, protein families that exist in effective pathogens will be discovered and may be predictive for organisms that have an unknown ecology or life strategy. Software for rapid analysis of bacterial genomic data to screen for pathogenic proteins has been designed, and similar tools and databases will be developed for fungal pathogens. (ii) Identification of potential pathogenicity factors, i.e., factors necessary for disease development that suppress or manipulate host-cell physiology to the advantage of a pathogen, but which are not essential for a pathogen to complete its life cycle. One example is disease effector proteins, which are likely expressed by all plant pathogens and may target similar defensive proteins in their hosts . Effector genes do not have conserved motifs in fungi, and identifiers in the genome, such as diversifying selection, will be crucial to identify these genes that may be a clue to pathogenicity. (iii) Identification of transposable elements or high mutation rates, which are implicated in the evolution of pathogenicity genes in fungi.

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11th International Congress of Plant Pathology (ICPP) on July 29 - August 3, 2018 in Boston, Massachusetts, U.S.A

11th International Congress of Plant Pathology (ICPP) on July 29 - August 3, 2018 in Boston, Massachusetts, U.S.A | Rice Blast | Scoop.it

The American Phytopathological Society (APS) is pleased to host the 11th International Congress of Plant Pathology (ICPP) on July 29 - August 3, 2018 in Boston, Massachusetts, U.S.A. As we prepare for the 2018 ICPP, the scientific program committee is seeking your input on what scientific content you deem important. Even if you are not attending, science discussions at the 2018 ICPP will have far reaching affects for plant pathology and related disciplines. We value your input, appreciate your time and hope you are able to attend the 2018 ICPP. We ask that you complete the survey by May 16, 2016. Thank you. Follow this link to the


Survey:


http://surveys.az1.qualtrics.com/SE/?SID=SV_1HpDGjVgcMlFYah

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Development of a High-Density Linkage Map and Tagging Leaf Spot Resistance in Pearl Millet Using Genotyping-by-Sequencing Markers

Development of a High-Density Linkage Map and Tagging Leaf Spot Resistance in Pearl Millet Using Genotyping-by-Sequencing Markers | Rice Blast | Scoop.it
Pearl millet [Pennisetum glaucum (L.) R. Br; also Cenchrus americanus (L.) Morrone] is an important forage and grain crop in many parts of the world but genomic resources for this species are needed to facilitate crop improvement.
The reference genetic map developed using 150 recombinant inbred lines contained 16,650 single-nucleotide polymorphisms and 333,567 sequence tags spread across all seven chromosomes.
This map is the densest yet reported for this crop and will be a valuable resource for the pearl millet community.
Genome mapping studies are a prerequisite for tagging agronomically important traits.
Genotyping-by-sequencing markers can be used to build high-density linkage maps, even in species lacking a reference genome.
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The Pmt2p-Mediated Protein O-Mannosylation Is Required for Morphogenesis, Adhesive Properties, Cell Wall Integrity and Full Virulence of Magnaporthe oryzae

The Pmt2p-Mediated Protein O-Mannosylation Is Required for Morphogenesis, Adhesive Properties, Cell Wall Integrity and Full Virulence of Magnaporthe oryzae | Rice Blast | Scoop.it
Protein O-mannosylation is a type of O-glycosylation that is characterized by the addition of mannose residues to target proteins, and is initially catalyzed by evolutionarily conserved protein O-mannosyltransferases (PMTs). In this study, three members of PMT were identified in Magnaporthe oryzae, and the pathogenic roles of MoPmt2, a member of PMT2 subfamily, were analyzed. We found that MoPmt2 is a homolog of Saccharomyces cerevisiae Pmt2 and could complement yeast Pmt2 function in resistance to CFW. Quantitative RT–PCR revealed that MoPmt2 is highly expressed during conidiation, and targeted disruption of MoPmt2 resulted in defects in conidiation and conidia morphology. The MoPmt2 mutants also showed a distinct reduction in fungal growth, which was associated with severe alterations in hyphal polarity. In addition, we found that the MoPmt2 mutants severely reduced virulence on both rice plants and barley leaves. The subsequent examination revealed that the fungal adhesion, conidial germination, CWI and invasive hyphae growth in host cells are responsible for defects on appressorium mediated penetration, and thus attenuated the pathogenicity of MoPmt2 mutants. Taken together, our results suggest that protein O-mannosyltransferase MoPmt2 plays essential roles in fungal growth and development, and is required for the full pathogenicity of M. oryzae.
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Self-assembly of MPG1, a hydrophobin protein from the rice blast fungus that forms functional amyloid coatings, occurs by a surface-driven mechanism

Self-assembly of MPG1, a hydrophobin protein from the rice blast fungus that forms functional amyloid coatings, occurs by a surface-driven mechanism | Rice Blast | Scoop.it
Rice blast is a devastating disease of rice caused by the fungus Magnaporthe oryzae and can result in loss of a third of the annual global rice harvest. Two hydrophobin proteins, MPG1 and MHP1, are highly expressed during rice blast infections. These hydrophobins have been suggested to facilitate fungal spore adhesion and to direct the action of the enzyme cutinase 2, resulting in penetration of the plant host. Therefore a mechanistic understanding of the self-assembly properties of these hydrophobins and their interaction with cutinase 2 is crucial for the development of novel antifungals. Here we report details of a study of the structure, assembly and interactions of these proteins. We demonstrate that, in vitro, MPG1 assembles spontaneously into amyloid structures while MHP1 forms a non-fibrillar film. The assembly of MPG1 only occurs at a hydrophobic:hydrophilic interface and can be modulated by MHP1 and other factors. We further show that MPG1 assemblies can much more effectively retain cutinase 2 activity on a surface after co-incubation and extensive washing compared with other protein coatings. The assembly and interactions of MPG1 and MHP1 at hydrophobic surfaces thereby provide the basis for a possible mechanism by which the fungus can develop appropriately at the infection interface.
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Large-scale rewiring of innate immunity circuitry and microRNA regulation during initial rice blast infection

Large-scale rewiring of innate immunity circuitry and microRNA regulation during initial rice blast infection | Rice Blast | Scoop.it
Rice blast is a recurrent fungal disease, and resistance to fungal infection is a complex trait. Therefore, a comprehensive examination of rice transcriptome and its variation during fungal infection is necessary to understand the complex gene regulatory networks. In this study, adopting Next-Generation Sequencing we profiled the transcriptomes and microRNAomes of rice varieties, one susceptible and the other resistant to M. oryzae, at multiple time points during the fungal infection. Our results revealed a substantial variation in the plant transcriptome and microRNAome as well as change to rice innate immunity during fungal infection. A number of putative R gene candidates were identified from a perturbed rice transcriptome analysis. The expression of genes and non-coding RNA molecules changed in both fungal resistant and susceptible plants during M. oryzae invasion discovered distinct pathways triggered in the susceptible and resistant plants. In addition, a number of fungus genes in the susceptible and resistant plants were constantly expressed at different time points, suggesting that they were likely to be the potential AVR genes. Our results revealed large-scale rewiring of innate immunity circuitry and microRNA regulation during initial rice blast infection, which would help to develop more robust blast-resistant rice plants.
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Activity profile of defence-related enzymes in rice genotypes (Oryza sativa L.) against rice blast (Magnaporthe oryzae)

The control and infected leaf samples of blast resistant and susceptible rice genotypes were evaluated for activities of defence-related enzymes viz., total phenol content, chitinase, phenylalanine ammonia lyase (PAL), β-glycosidase, antioxidative enzymes, superoxide dismutase, peroxidase and ascorbate peroxidase. The level of total phenol content and the activity profile of chitinase, PAL and β-glycosidase significantly increased in both blast-resistant and susceptible rice genotypes with comparatively higher level induction Tetep, NLR-20104 and Swarnadhan the blast-resistant genotypes. The antioxidative enzymes were comparatively higher in the leaf samples of blast-resistant genotypes recording highest increase in NLR-20104 and KJT-5. The constitutive levels of total phenols and activity of defence-related and antioxidative enzymes in the control leaf samples differed among the genotypes and were even higher in the two blast susceptible genotypes (EK-70 and Chimansal). However, the level of induction as evident from the activity profile differences between control and infected leaf samples suggests higher level of induction was more which is indicative of the induced defence response. The genotype recording maximum induction of defence-related and antioxidative enzymes activity could be useful criteria in screening for blast resistant genotype in rice.
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