Wheat blast disease management: cues from the advancements in molecular biology of rice-Magnaporthe pathosystem

Rapid detection is key to managing emerging diseases because it allows their spread around the world to be monitored and limited. The first major wheat blast epidemics were reported in 1985 in the Brazilian state of Paraná. Following this outbreak, the disease quickly spread to neighboring regions and countries and, in 2016, the first report of wheat blast disease outside South America was released. This Asian outbreak was due to the trade of infected South American seed, demonstrating the importance of detection tests in order to avoid importing contaminated biological material into regions free from the pathogen. Genomic analysis has revealed that one particular lineage within the fungal species Pyricularia oryzae is associated with this disease: the Triticum lineage. A comparison of 81 Pyricularia genomes highlighted polymorphisms specific to the Triticum lineage, and this study developed a real-time PCR test targeting one of these polymorphisms. The test’s performance was then evaluated in order to measure its analytical specificity, analytical sensitivity, and robustness. The C17 quantitative PCR test detected isolates belonging to the Triticum lineage with high sensitivity, down to 13 plasmid copies or 1 pg of genomic DNA per reaction tube. The blast-based approach developed here to study P. oryzae can be transposed to other emerging diseases.

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Mitigating the twin problems of malnutrition and wheat blast by one wheat variety, ‘BARI Gom 33’, in Bangladesh

Acta Agrobotanica ◽

10.5586/aa.1775 ◽

2019 ◽

Vol 72 (2) ◽

Cited By ~ 2

Author(s):

Akbar Hossain ◽

Khondoker Abdul Mottaleb ◽

Md. Farhad ◽

Naresh Chandra Deb Barma

Keyword(s):

South Asia ◽

Wheat Variety ◽

Climatic Conditions ◽

Blast Disease ◽

Zn Deficiency ◽

Wheat Blast ◽

Positive Externalities ◽

The Status ◽

Maize Research Institute ◽

Scaling Out

For the first time in history outside of Latin America, deadly wheat blast caused by the fungus Magnaporthe oryzae pathotype triticum (MoT) emerged in the 2015–2016 wheat (Triticum aestivum L.) season of Bangladesh. Bangladesh, a country in South Asia, has a population of nearly 160 million, of which 24.3% are classified as poor. Consequently, malnutrition and micronutrient deficiency are highly prevalent, particularly among school going children and lactating women. Bangladesh Wheat and Maize Research Institute (BWMRI), with the technical support of the International Maize and Wheat Improvement Center (CIMMYT), Mexico, has developed and released a new wheat ‘BARI Gom 33’. The new wheat is a zinc-enriched (Zn) biofortified wheat, resistant to the deadly wheat blast disease. ‘BARI Gom 33’ provides 5–8% more yield than the check varieties in Bangladesh. Rapid dissemination of it in Bangladesh, therefore, can not only combat wheat blast but also mitigate the problem of Zn deficiency and ensure income for resource-poor wheat farmers. Importantly, a large portion of the current wheat area in India and Pakistan is vulnerable to wheat blast, due to the similarities of the agro-climatic conditions of Bangladesh. As wheat blast is mainly a seed-borne disease, a rapid scaling out of the new wheat in Bangladesh can reduce the probability of MoT intrusion in India and Pakistan, and thereby generate positive externalities to the food security of more than 1 billion people in South Asia. This study explains the development process of ‘BARI Gom 33’; the status of malnutrition in Bangladesh, and the possible economic gain from a rapid scaling out of ‘BARI Gom 33’ in Bangladesh. A few policies are recommended based on the discussions.

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Effector Gene Reshuffling Involves Dispensable Mini-chromosomes in the Wheat Blast Fungus

10.1101/359455 ◽

2018 ◽

Cited By ~ 3

Author(s):

Zhao Peng ◽

Ely Oliveira Garcia ◽

Guifang Lin ◽

Ying Hu ◽

Melinda Dalby ◽

...

Keyword(s):

Rice Blast ◽

Field Isolate ◽

Rice Blast Disease ◽

Blast Disease ◽

Long Distance ◽

Wheat Blast ◽

Effector Genes ◽

Long Read ◽

Evolutionary Trajectories ◽

End Sequences

AbstractNewly emerged wheat blast disease is a serious threat to global wheat production. Wheat blast is caused by a distinct, exceptionally diverse lineage of the fungus causing rice blast disease. To understand genetic diversity in wheat-infecting strains, we report a near-finished reference genome of a recent field isolate generated using long read sequencing and a novel scaffolding approach with long-distance paired genomic sequences. The genome assemblage includes seven core chromosomes and sequences from a dispensable mini-chromosome that harbors effector genes normally found on the ends of core chromosomes in other strains. No mini-chromosomes were observed in an early field strain, and two mini-chromosomes from another field isolate each contain different effector homologous genes and core chromosome end sequences. The mini-chromosome is highly repetitive and is enriched in transposons occurring most frequently at core chromosome ends. Additionally, transposons in mini-chromosomes lack the characteristic signature for inactivation by repeat-induced point (RIP) mutation genome defenses. Our results, collectively, indicate that dispensable mini-chromosomes and non-dispensable core chromosomes undergo divergent evolutionary trajectories, and mini-chromosomes and core chromosome ends are coupled as a mobile, fast-evolving effector compartment in the wheat pathogen genome.Significance statementThe emerging blast disease on wheat is proving even harder to control than the ancient, still-problematic rice blast disease. Potential wheat resistance identified using strains isolated soon after disease emergence are no longer effective in controlling recent aggressive field isolates from wheat in South America and South Asia. We report that recent wheat pathogens can contain one or two highly-variable conditionally-dispensable mini-chromosomes, each with an amalgamation of effector sequences that are duplicated or absent from pathogen core chromosome ends. Well-studied effectors found on different core chromosomes in rice pathogens appear side-by-side in wheat pathogen mini-chromosomes. The rice pathogen often overcomes deployed resistance genes by deleting triggering effector genes. Localization of effectors on mini-chromosomes, which are unstably transmitted during growth, would accelerate pathogen adaptation in the field.

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Soil supplementation with Si, B and Zn and their synergetic effects in reducing severity of wheat blast (Magnaporthe oryzae Triticum)

International Journal of Agricultural Research Innovation and Technology ◽

10.3329/ijarit.v11i2.57259 ◽

2022 ◽

Vol 11 (2) ◽

pp. 76-84

Author(s):

MH Kabir ◽

HR Nayan ◽

MA Abedin ◽

MB Meah

Keyword(s):

Magnaporthe Oryzae ◽

Susceptible Variety ◽

Blast Disease ◽

Management Approach ◽

Limiting Factor ◽

Wheat Blast ◽

Soil Preparation ◽

Cropping Seasons ◽

House Condition ◽

Chemical Pesticides

Wheat blast (Magnaporthe oryzae Triticum) in Bangladesh and South America is recognized as one major limiting factor of wheat production. Its control using chemical pesticides raises concerns about food safety and pesticide resistance, which have dictated the need for alternative blast management approach, nutrient supplementation could be an ecofriendly alternative. Experiments were carried out under confined net house condition for two consecutive cropping seasons. Single doses of the nutrients (Si, B and Zn) were incorporated during soil preparation. Plants of the wheat blast susceptible variety BARI Gom-26 were inoculated with spores (1 x 107 spores ml-1) of Magnaporthe oryzae Triticum at blast vulnerable pre-heading stage of 52 days age. Typical wheat blast symptoms of spike bleaching from top to downward appeared on sight 14 days after inoculation i.e., 66 days age of the crop. Incidence and severity of blast bleaching of spike were scored for four times starting from 68 days age @ three day’s interval. None of the nutrients could stop the incidence of blast on wheat; however, some nutrients reduced the blast incidence significantly. Solo application of Si, B and Zn or combination of two caused significant reduction of spike bleaching. With the mixed application of Si, B and Zn, > 47% reduction of wheat blast severity was obtained. The results revealed that the soil application of silicon, zinc and boron had a synergistic effect on the intensity of blast disease of wheat. Int. J. Agril. Res. Innov. Tech. 11(2): 76-84, Dec 2021

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Wheat Blast: Past, Present, and Future

Annual Review of Phytopathology ◽

10.1146/annurev-phyto-080417-050036 ◽

2018 ◽

Vol 56 (1) ◽

pp. 427-456 ◽

Cited By ~ 28

Author(s):

Paulo Cezar Ceresini ◽

Vanina Lilián Castroagudín ◽

Fabrício Ávila Rodrigues ◽

Jonas Alberto Rios ◽

Carlos Eduardo Aucique-Pérez ◽

...

Keyword(s):

Current Knowledge ◽

Phenotypic Diversity ◽

Integrated Management ◽

Durable Resistance ◽

Management Strategies ◽

Blast Disease ◽

Broad Host Range ◽

Wheat Varieties ◽

Wheat Blast ◽

Grass Hosts

The devastating wheat blast disease first emerged in Brazil in 1985. The disease was restricted to South America until 2016, when a series of grain imports from Brazil led to a wheat blast outbreak in Bangladesh. Wheat blast is caused by Pyricularia graminis-tritici ( Pygt), a species genetically distinct from the Pyricularia oryzae species that causes rice blast. Pygt has high genetic and phenotypic diversity and a broad host range that enables it to move back and forth between wheat and other grass hosts. Recombination is thought to occur mainly on the other grass hosts, giving rise to the highly diverse Pygt population observed in wheat fields. This review brings together past and current knowledge about the history, etiology, epidemiology, physiology, and genetics of wheat blast and discusses the future need for integrated management strategies. The most urgent current need is to strengthen quarantine and biosafety regulations to avoid additional spread of the pathogen to disease-free countries. International breeding efforts will be needed to develop wheat varieties with more durable resistance.

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Beating the beast-wheat blast disease

Improving Cereal Productivity Through Climate Smart Practices ◽

10.1016/b978-0-12-821316-2.00012-1 ◽

2021 ◽

pp. 205-223

Author(s):

Santosh Kumar Bishnoi ◽

Rahul Madhavrao Phuke ◽

Muhammad Rezaul Kabir ◽

Krishna Kanta Roy ◽

Felix Marza ◽

...

Keyword(s):

Blast Disease ◽

Wheat Blast

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Molecular Biology in Plant Pathogenesis and Disease Management

10.1007/978-1-4020-8243-6 ◽

2008 ◽

Keyword(s):

Disease Management ◽

Molecular Biology ◽

Plant Pathogenesis

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Molecular Biology in Plant Pathogenesis and Disease Management

10.1007/978-1-4020-8245-0 ◽

2008 ◽

Keyword(s):

Disease Management ◽

Molecular Biology ◽

Plant Pathogenesis

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Gene Flow between Divergent Cereal- and Grass-Specific Lineages of the Rice Blast Fungus Magnaporthe oryzae

mBio ◽

10.1128/mbio.01219-17 ◽

2018 ◽

Vol 9 (1) ◽

Cited By ~ 54

Author(s):

Pierre Gladieux ◽

Bradford Condon ◽

Sebastien Ravel ◽

Darren Soanes ◽

Joao Leodato Nunes Maciel ◽

...

Keyword(s):

Gene Flow ◽

South America ◽

Magnaporthe Oryzae ◽

Rice Blast ◽

Evolutionary History ◽

Blast Disease ◽

Whole Genome ◽

Disease Emergence ◽

Wheat Blast ◽

History Of

ABSTRACT Delineating species and epidemic lineages in fungal plant pathogens is critical to our understanding of disease emergence and the structure of fungal biodiversity and also informs international regulatory decisions. Pyricularia oryzae (syn. Magnaporthe oryzae) is a multihost pathogen that infects multiple grasses and cereals, is responsible for the most damaging rice disease (rice blast), and is of growing concern due to the recent introduction of wheat blast to Bangladesh from South America. However, the genetic structure and evolutionary history of M. oryzae, including the possible existence of cryptic phylogenetic species, remain poorly defined. Here, we use whole-genome sequence information for 76 M. oryzae isolates sampled from 12 grass and cereal genera to infer the population structure of M. oryzae and to reassess the species status of wheat-infecting populations of the fungus. Species recognition based on genealogical concordance, using published data or extracting previously used loci from genome assemblies, failed to confirm a prior assignment of wheat blast isolates to a new species (Pyricularia graminis-tritici). Inference of population subdivisions revealed multiple divergent lineages within M. oryzae, each preferentially associated with one host genus, suggesting incipient speciation following host shift or host range expansion. Analyses of gene flow, taking into account the possibility of incomplete lineage sorting, revealed that genetic exchanges have contributed to the makeup of multiple lineages within M. oryzae. These findings provide greater understanding of the ecoevolutionary factors that underlie the diversification of M. oryzae and highlight the practicality of genomic data for epidemiological surveillance in this important multihost pathogen. IMPORTANCE Infection of novel hosts is a major route for disease emergence by pathogenic microorganisms. Understanding the evolutionary history of multihost pathogens is therefore important to better predict the likely spread and emergence of new diseases. Magnaporthe oryzae is a multihost fungus that causes serious cereal diseases, including the devastating rice blast disease and wheat blast, a cause of growing concern due to its recent spread from South America to Asia. Using whole-genome analysis of 76 fungal strains from different hosts, we have documented the divergence of M. oryzae into numerous lineages, each infecting a limited number of host species. Our analyses provide evidence that interlineage gene flow has contributed to the genetic makeup of multiple M. oryzae lineages within the same species. Plant health surveillance is therefore warranted to safeguard against disease emergence in regions where multiple lineages of the fungus are in contact with one another.

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