scholarly journals COEVOLUTION WITH SPATIALLY STRUCTURED RICE LANDRACES MAINTAINS MULTIPLE GENERALIST LINEAGES IN THE RICE BLAST PATHOGEN

2021 ◽  
Author(s):  
Sajid Ali ◽  
Pierre Gladieux ◽  
Sebastien Ravel ◽  
Henri Adreit ◽  
Isabelle Meusnier ◽  
...  
Keyword(s):  
Rice Blast ◽  
Life Histories ◽  
Control Strategies ◽  
Indica Rice ◽  
Disease Outbreaks ◽  
Population Subdivision ◽  
Disease Dynamics ◽  
Rice Landraces ◽  
Scale Population ◽  
Significant Disease

Traditional agrosystems, where humans, crops and microbes have coevolved over long periods, can serve as models to understand the eco-evolutionary determinants of disease dynamics and help the engineering of durably resistant agrosystems. Here, we investigated the genetic and phenotypic relationship between rice (Oryza sativa) landraces and their rice blast pathogen (Magnaporthe oryzae) in the traditional Yuanyang terraces of flooded rice paddies in China, where rice landraces have been grown and bred over centuries without significant disease outbreaks. Analyses of genetic subdivision revealed that indica rice plants clustered according to landrace names. Three new diverse lineages of rice blast specific to the Yuanyang terraces coexisted with lineages previously detected at the worldwide scale. Population subdivision in the pathogen population did not mirror pattern of population subdivision in the host. Measuring the pathogenicity of rice blast isolates on landraces revealed generalist life histories. Our results suggest that the implementation of disease control strategies based on the emergence or maintenance of a generalist lifestyle in pathogens may sustainably reduce the burden of disease in crops.

scholarly journals Sustainable production and use of cleaner fish for the biological control of sea lice: recent advances and current challenges

2018 ◽  
Vol 183 (12) ◽  
pp. 383-383 ◽  
Author(s):  
Adam J Brooker ◽  
Athina Papadopoulou ◽  
Carolina Gutierrez ◽  
Sonia Rey ◽  
Andrew Davie ◽  
...  
Keyword(s):  
Life Histories ◽  
Control Strategies ◽  
Disease Outbreaks ◽  
Basic Knowledge ◽  
Sea Lice ◽  
Suitable Habitat ◽  
Farmed Fish ◽  
Marine Aquaculture ◽  
Cleaner Fish ◽  
Labrus Bergylta

Currently, cleaner fish are one of the most widely used sea lice control strategies in Atlantic salmon aquaculture. Two species are currently being farmed in North Atlantic countries, ballan wrasse (Labrus bergylta) and lumpfish (Cyclopterus lumpus), and the sector in most countries is rapidly expanding towards self-sufficiency. The species are very different both in terms of their biology and life histories and, consequently, production and husbandry methods must be tailored to each species. There are numerous health challenges currently experienced in both species, with bacterial and parasitic diseases being the most prevalent, and cohabitation with salmon may increase the risk of disease. Good husbandry and routine health monitoring are essential, although treatment is often required when disease outbreaks occur. Ballan wrasse and lumpfish are both proven to be effective salmon delousers, although delousing efficacy can be variable in farmed fish; the provision of suitable habitat and acclimation to net-pen conditions may encourage natural behaviours, including delousing, and the use of operational welfare indicators can highlight potential welfare issues. Cleaner fish research is progressing rapidly, although much of the basic knowledge regarding the species’ biology remains unknown. The simultaneous domestication of two new marine aquaculture species is a significant challenge demanding sustained effort and funding over a prolonged period of time. Research must focus on enhancing the robustness of the farmed stocks and increasing hatchery outputs to meet the urgent demands from the salmon sector and protect wild stocks from overfishing.

scholarly journals Coexistence of multiple endemic and pandemic lineages of the rice blast pathogen

2017 ◽  
Author(s):  
Pierre Gladieux ◽  
Sébastien Ravel ◽  
Adrien Rieux ◽  
Sandrine Cros-Arteil ◽  
Henri Adreit ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Control Strategies ◽  
Indica Rice ◽  
Rice Blast Fungus ◽  
Pyricularia Oryzae ◽  
Effective Control ◽  
Sexual Recombination ◽  
Japonica And Indica Rice

AbstractThe rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae) is both a threat to global food security and a model for plant pathology. Molecular pathologists need an accurate understanding of the origins and line of descent of M. oryzae populations, to identify the genetic and functional bases of pathogen adaptation, and to guide the development of more effective control strategies. We used a whole-genome sequence analysis of samples from different times and places to infer details about the genetic makeup of M. oryzae from a global collection of isolates. Analyses of population structure identified six lineages within M. oryzae, including two pandemic on japonica and indica rice, respectively, and four lineages with more restricted distributions. Tip-dating calibration indicated that M. oryzae lineages separated about a millenium ago, long after the initial domestication of rice. The major lineage endemic to continental Southeast Asia displayed signatures of sexual recombination and evidence of DNA acquisition from multiple lineages. Tests for weak natural selection revealed that the pandemic spread of clonal lineages entailed an evolutionary ‘cost’, in terms of the accumulation of deleterious mutations. Our findings reveal the coexistence of multiple endemic and pandemic lineages with contrasting population and genetic characteristics within a widely distributed pathogen.ImportanceThe rice blast fungus Magnaporthe oryzae (syn. Pyricularia oryzae) is a textbook example of a rapidly adapting pathogen, and is responsible for one of the most damaging diseases of rice. Improvements in our understanding of Magnaporthe oryzae diversity and evolution are required, to guide the development of more effective control strategies. We used genome sequencing data for samples from around the world to infer the evolutionary history of M. oryzae. We found that M. oryzae diversified about a thousand years ago ago, separating into six main lineages: two pandemic on japonica and indica rice, respectively, and four with more restricted distributions. We also found that a lineage endemic to continental Southeast Asia displayed signatures of sexual recombination and the acquisition of genetic material from multiple lineages. This work provides a population-level genomic framework for defining molecular markers for the control of rice blast and investigations of the molecular basis of differences in pathogenicity between M. oryzae lineages.

scholarly journals Coexistence of Multiple Endemic and Pandemic Lineages of the Rice Blast Pathogen

mBio ◽  
2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Pierre Gladieux ◽  
Sébastien Ravel ◽  
Adrien Rieux ◽  
Sandrine Cros-Arteil ◽  
Henri Adreit ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Control Strategies ◽  
Indica Rice ◽  
Rice Blast Fungus ◽  
Effective Control ◽  
Content Type ◽  
Sexual Recombination ◽  
Japonica And Indica Rice

ABSTRACTThe rice blast fungusMagnaporthe oryzae(syn.,Pyricularia oryzae) is both a threat to global food security and a model for plant pathology. Molecular pathologists need an accurate understanding of the origins and line of descent ofM. oryzaepopulations in order to identify the genetic and functional bases of pathogen adaptation and to guide the development of more effective control strategies. We used a whole-genome sequence analysis of samples from different times and places to infer details about the genetic makeup ofM. oryzaefrom a global collection of isolates. Analyses of population structure identified six lineages withinM. oryzae, including two pandemic on japonica and indica rice, respectively, and four lineages with more restricted distributions. Tip-dating calibration indicated thatM. oryzaelineages separated about a millennium ago, long after the initial domestication of rice. The major lineage endemic to continental Southeast Asia displayed signatures of sexual recombination and evidence of DNA acquisition from multiple lineages. Tests for weak natural selection revealed that the pandemic spread of clonal lineages entailed an evolutionary “cost,” in terms of the accumulation of deleterious mutations. Our findings reveal the coexistence of multiple endemic and pandemic lineages with contrasting population and genetic characteristics within a widely distributed pathogen.IMPORTANCEThe rice blast fungusMagnaporthe oryzae(syn.,Pyricularia oryzae) is a textbook example of a rapidly adapting pathogen, and it is responsible for one of the most damaging diseases of rice. Improvements in our understanding ofMagnaporthe oryzae’s diversity and evolution are required to guide the development of more effective control strategies. We used genome sequencing data for samples from around the world to infer the evolutionary history ofM. oryzae. We found thatM. oryzaediversified about 1,000 years ago, separating into six main lineages: two pandemic on japonica and indica rice, respectively, and four with more restricted distributions. We also found that a lineage endemic to continental Southeast Asia displayed signatures of sexual recombination and the acquisition of genetic material from multiple lineages. This work provides a population-level genomic framework for defining molecular markers for the control of rice blast and investigations of the molecular basis of differences in pathogenicity betweenM. oryzaelineages.

scholarly journals Extinction and persistence of a stochastic SIRV epidemic model with nonlinear incidence rate

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Ramziya Rifhat ◽  
Zhidong Teng ◽  
Chunxia Wang
Keyword(s):  
Epidemic Model ◽  
Control Strategies ◽  
Random Perturbations ◽  
Disease Dynamics ◽  
Nonlinear Incidence Rate ◽  
Nonlinear Incidence ◽  
Analysis Theory ◽  
Lyapunov Function Method ◽  
Random Fluctuations ◽  
Theoretical Results

AbstractIn this paper, a stochastic SIRV epidemic model with general nonlinear incidence and vaccination is investigated. The value of our study lies in two aspects. Mathematically, with the help of Lyapunov function method and stochastic analysis theory, we obtain a stochastic threshold of the model that completely determines the extinction and persistence of the epidemic. Epidemiologically, we find that random fluctuations can suppress disease outbreak, which can provide us some useful control strategies to regulate disease dynamics. In other words, neglecting random perturbations overestimates the ability of the disease to spread. The numerical simulations are given to illustrate the main theoretical results.

scholarly journals Fighting a fire versus waiting for a wave: Useful and not-so-useful analogies in times of SARS-CoV-2

2021 ◽  
Author(s):  
Louise Archer ◽  
Claire Standley ◽  
Péter Molnár
Keyword(s):  
Public Health ◽  
Control Strategies ◽  
Spatial Dynamics ◽  
Disease Outbreak ◽  
Biological Processes ◽  
Disease Dynamics ◽  
Epidemiological Models ◽  
Communication Tools ◽  
Regular Feature ◽  
News Headlines

As SARS-CoV-2 has swept the planet, intermittent “lockdowns” have become a regular feature to control transmission. References to so-called recurring “waves” of infections remain pervasive among news headlines, political messaging, and public health sources. Here, we consider the power of analogies as a tool for facilitating effective understanding of biological processes by reviewing the successes and limitations of various analogies in the context of the COVID-19 pandemic. We also consider how, when analogies fall short, their ability to persuade can mislead public opinion and behaviour, even if unintentionally. While waves can be effective in conveying patterns of disease outbreak retrospectively, we suggest that process-based analogies might be more effective communication tools, given that they are easily mapped to underlying epidemiological concepts and can be extended to include more complex (e.g., spatial) dynamics. Though no single analogy perfectly captures disease dynamics, fire is particularly suitable for visualizing the epidemiological models that are used to understand disease trajectories, underscoring the importance of and reasoning behind control strategies, and, above all, conveying a sense of urgency to galvanise collective action.

scholarly journals Mosquitoes of Etiological Concern in Kenya and Possible Control Strategies

Insects ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 173 ◽  
Author(s):  
Samuel Karungu ◽  
Evans Atoni ◽  
Joseph Ogalo ◽  
Caroline Mwaliko ◽  
Bernard Agwanda ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Mosquito Control ◽  
Control Strategies ◽  
Mosquito Species ◽  
Disease Outbreaks ◽  
Health Concern ◽  
Public Health Concern ◽  
Vector Management ◽  
Invasive Mosquito ◽  
Parasitic Pathogens

Kenya is among the most affected tropical countries with pathogen transmitting Culicidae vectors. For decades, insect vectors have contributed to the emergence and distribution of viral and parasitic pathogens. Outbreaks and diseases have a great impact on a country’s economy, as resources that would otherwise be used for developmental projects are redirected to curb hospitalization cases and manage outbreaks. Infected invasive mosquito species have been shown to increasingly cross both local and global boarders due to the presence of increased environmental changes, trade, and tourism. In Kenya, there have been several mosquito-borne disease outbreaks such as the recent outbreaks along the coast of Kenya, involving chikungunya and dengue. This certainly calls for the implementation of strategies aimed at strengthening integrated vector management programs. In this review, we look at mosquitoes of public health concern in Kenya, while highlighting the pathogens they have been linked with over the years and across various regions. In addition, the major strategies that have previously been used in mosquito control and what more could be done to reduce or combat the menace caused by these hematophagous vectors are presented.

scholarly journals Induced Resistance for Plant Disease Control: Maximizing the Efficacy of Resistance Elicitors

2005 ◽  
Vol 95 (12) ◽  
pp. 1368-1373 ◽  
Author(s):  
Dale Walters ◽  
David Walsh ◽  
Adrian Newton ◽  
Gary Lyon
Keyword(s):  
Disease Control ◽  
Induced Resistance ◽  
Management Practices ◽  
Control Strategies ◽  
Plant Growth Promoting Rhizobacteria ◽  
Complete Control ◽  
Plant Disease Control ◽  
Plant Growth Promoting ◽  
Significant Disease ◽  
Best Fit

Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as “safe fungicides”. This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use.

A genetic-epidemiological model for Marek’s Disease in Poultry

2009 ◽  
Vol 2009 ◽  
pp. 197-197
Author(s):  
M Nath ◽  
S C Bishop
Keyword(s):  
Control Strategies ◽  
Epidemiological Model ◽  
Marek's Disease ◽  
Disease Dynamics ◽  
Marek’S Disease ◽  
Parameter Spaces ◽  
Gene Markers ◽  
Poultry Breeding ◽  
Breeding Programmes ◽  
Or Gene

Marek’s disease (MD), caused by a herpes virus, is a very infectious, lymphoproliferative and chronic disease of poultry. Breeding for improved MD resistance poultry stock is possible since MD resistance has been associated with MHC haplotypes, QTL and candidate genes. However, integration of host genetics vis-à-vis other control strategies and the utilisation of genes or gene markers for MD in practical breeding programmes is still a challenge. The objective of the present study was to develop a basic genetic-epidemiological model for Marek’s disease infection in poultry, identify parameter spaces that describe the disease dynamics correctly and investigate the impacts of possible genetic and vaccination control strategies on overall disease dynamics.

scholarly journals Foot-and-Mouth Disease

2004 ◽  
Vol 17 (2) ◽  
pp. 465-493 ◽  
Author(s):  
Marvin J. Grubman ◽  
Barry Baxt
Keyword(s):  
Control Strategies ◽  
Disease Outbreaks ◽  
Foot And Mouth Disease ◽  
Developed Countries ◽  
Etiologic Agent ◽  
Mouth Disease ◽  
Receptor Interactions ◽  
Foot And Mouth ◽  
Virus Replication Cycle ◽  
Disease Free

SUMMARY Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals. The disease was initially described in the 16th century and was the first animal pathogen identified as a virus. Recent FMD outbreaks in developed countries and their significant economic impact have increased the concern of governments worldwide. This review describes the reemergence of FMD in developed countries that had been disease free for many years and the effect that this has had on disease control strategies. The etiologic agent, FMD virus (FMDV), a member of the Picornaviridae family, is examined in detail at the genetic, structural, and biochemical levels and in terms of its antigenic diversity. The virus replication cycle, including virus-receptor interactions as well as unique aspects of virus translation and shutoff of host macromolecular synthesis, is discussed. This information has been the basis for the development of improved protocols to rapidly identify disease outbreaks, to differentiate vaccinated from infected animals, and to begin to identify and test novel vaccine candidates. Furthermore, this knowledge, coupled with the ability to manipulate FMDV genomes at the molecular level, has provided the framework for examination of disease pathogenesis and the development of a more complete understanding of the virus and host factors involved.

Sign in / Sign up

Export Citation Format

Share Document