scholarly journals Genetic variation and host-parasite specificity ofStrigaresistance and tolerance in rice: the need for predictive breeding

2017 ◽  
Vol 214 (3) ◽  
pp. 1267-1280 ◽  
Author(s):  
Jonne Rodenburg ◽  
Mamadou Cissoko ◽  
Nicholas Kayongo ◽  
Ibnou Dieng ◽  
Jenipher Bisikwa ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Parasite Specificity ◽  
Host Parasite

scholarly journals Genetic variation in dispersal plasticity in an aquatic host-parasite model system

2020 ◽  
Author(s):  
Giacomo Zilio ◽  
Louise Solveig Noergaard ◽  
Giovanni Petrucci ◽  
Nathalie Zeballos ◽  
Claire Gougat-Barbera ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Internal State ◽  
Theoretical Models ◽  
Infection Prevalence ◽  
Main Role ◽  
Dependent Plasticity ◽  
Evolutionary Forces ◽  
State Dependent ◽  
Context Dependent ◽  
Host Parasite

Dispersal plays a main role in determining spatial dynamics, and both theory and empirical evidence indicate that evolutionary optima exist for constitutive or plastic dispersal behaviour. Plasticity in dispersal can be influenced by factors both internal (state-dependent) or external (context-dependent) to individuals. Parasitism is interesting in this context, as it can influence both types of host dispersal plasticity: individuals can disperse in response to internal infection status but might also respond to the presence of infected individuals around them. We still know little about the driving evolutionary forces of host dispersal plasticity, but a first requirement is the presence of a genetic basis on which natural selection can act. In this study, we used microcosm dispersal mazes to investigate plastic dispersal of 20 strains of the freshwater protist Paramecium caudatum in response to the bacterial parasite Holospora undulata. We additionally quantified the genetic component of the plastic responses, i.e. the heritability of state- and context-depended dispersal. We found that infection by the parasite can either increase or decrease dispersal of individual strains relative to the uninfected (state-dependent plasticity), and this to be heritable. We also found strain-specific change of dispersal of uninfected Paramecium when exposed to variable infection prevalence (context-dependent plasticity) with very low level of heritability. To our knowledge, this is the first explicit empirical demonstration and quantification of genetic variation of plastic dispersal in a host-parasite system, which could have important implications for meta-population and epidemiological dynamics. We discuss some of the underlying mechanisms of this variation and link our results to the existing theoretical models.

scholarly journals Dolops carvalhoi as a vector of Epistylis sp. between cultivated and wild specimens of Oreochromis niloticus in Brazil

2019 ◽  
Vol 28 (2) ◽  
pp. 325-329
Author(s):  
Cibele Diogo Pagliarini ◽  
Lidiane Franceschini ◽  
Cristiéle da Silva Ribeiro ◽  
Rosilene Luciana Delariva ◽  
João Paulo de Arruda Amorim ◽  
...  
Keyword(s):  
Geographical Distribution ◽  
Oreochromis Niloticus ◽  
Production Systems ◽  
Preventive Measure ◽  
Fish Farms ◽  
Accidental Release ◽  
Parasite Specificity ◽  
Etiological Agents ◽  
Host Parasite ◽  
Cage Fish

Abstract Epistyliasis has been characterized as an emergent disease which has a great impact on fish farms, especially on Oreochromis niloticus production systems. Although epidemiological important, information about the dispersion of these parasites and their mechanical vectors is scarce. The present study reported the cooccurrence of Epistylis sp. as an epibiont of Dolops carvalhoi, a parasitic crustacean of cultivated/wild specimens (from accidental release) of O. niloticus from a cage fish farm area in the Ilha Solteira Reservoir, Grande River, SP, Brazil. The co-occurrence of Epistylis sp. and D. carvalhoi, and their epibiont relationship registered in this study suppose that the Epistylis may use the crustaceans for dispersion and as mechanical vectors for the dissemination of diseases in wild and cultivated hosts. Moreover, exchange of parasites between wild and cultivated hosts is possible, considering both organisms (protozoan and argulid). Furthermore, the results of the present study demonstrate the need to monitor the areas adjacent to cage fish farms as a preventive measure for the dispersion of pathogens. This is the first report of epibiosis between Epistylis sp. and argulid parasites of cultivated and wild O. niloticus, contributing to knowledge about host-parasite specificity, geographical distribution, dispersion of etiological agents and epidemiology in aquaculture.

Parasitism of oospores of Pythium spp. by strains of Actinoplanes spp.

1993 ◽  
Vol 39 (10) ◽  
pp. 964-972 ◽  
Author(s):  
N. I. Khan ◽  
A. B. Filonow ◽  
L. L. Singleton ◽  
M. E. Payton
Keyword(s):  
Biological Control ◽  
Host Specificity ◽  
Pythium Ultimum ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
Pythium Arrhenomanes ◽  
Parasite Specificity ◽  
Host Parasite ◽  
First Time

Strains of Actinoplanes spp. were evaluated for their in vitro parasitism of oospores of Pythium aphanidermatum, Pythium arrhenomanes, Pythium irregulare, Pythium myriotylum, and Pythium ultimum. Oospores of Pythium arrhenomanes, Pythium irregulare, and Pythium myriotylum were identified for the first time as hosts of Actinoplanes spp. Newly recorded parasites of oospores of Pythium spp. were Actinoplanes azureus, Actinoplanes brasiliensis, Actinoplanes caeruleus, Actinoplanes ferrugineus, Actinoplanes ianthinogenes, Actinoplanes italicus, Actinoplanes minutisporangius, Actinoplanes rectilineatus, Actinoplanes teichomyceticus, Actinoplanes utahensis, Actinoplanes violaceous, Actinoplanes yunnahenis, plus 15 strains of Actinoplanes yet to be speciated. Parasitized oospores had disorganized cytoplasms and hyphae of Actinoplanes sp. emerging from them. Infection of oospores in vitro varied from 0 to > 90%. Strains also were very active parasites of oospores in sterile soils. When added to nonsterile soils, several strains increased (p = 0.05) the level of oospore parasitism compared with nonsupplemented soils. Strains of Actinoplanes spp. exhibited a host specificity for species of Pythium in vitro and in soil. Sporulation of Actinoplanes sp. from infected oospores incubated on soil was frequent and more abundant than that observed in vitro.Key words: Pythium spp., Actinoplanes spp., actinomycetes, biological control, host–parasite specificity.

Injury-related phaseollin accumulation in Phaseolus vulgaris and its implications with regard to specificity of host–parasite interaction

1975 ◽  
Vol 53 (9) ◽  
pp. 921-928 ◽  
Author(s):  
James E. Rahe ◽  
Robert M. Arnold
Keyword(s):  
Phaseolus Vulgaris ◽  
Colletotrichum Lindemuthianum ◽  
Living Tissue ◽  
Cotyledonary Nodes ◽  
Etiolated Seedlings ◽  
Parasite Specificity ◽  
Per Se ◽  
Freezing Injuries ◽  
Host Parasite ◽  
Time Point

Phaseollin accumulated locally at point-freezing injuries on hypocotyls of intact etiolated seedlings of Phaseolus vulgaris. Maximum amounts occurred within 24 to 30 h after injury. Smaller amounts accumulated at similar sites on hypocotyls excised at the time point-freezing injuries were made, and the accumulation was less localized. Increasing amounts of phaseollin occurred at sites increasingly distant from the cotyledonary nodes in both intact and excised hypocotyls. Much higher levels of phaseollin were elicited by excision per se than by point-freezing. Phaseollin was not detected after freezing of whole hypocotyls, indicating that living tissue adjacent to injuries is required for accumulation. The data are discussed in relation to host–parasite specificity, with particular reference to the interaction between P. vulgaris and Colletotrichum lindemuthianum.

A Generalized Concept of Host-Parasite Specificity

1981 ◽  
Vol 71 (11) ◽  
pp. 1121 ◽  
Author(s):  
Michele C. Heath
Keyword(s):  
Parasite Specificity ◽  
Host Parasite

Variation in the host-parasite relationship of a crop disease

1968 ◽  
Vol 71 (1) ◽  
pp. 19-36 ◽  
Author(s):  
M. H. Arnold ◽  
S. J. Brown
Keyword(s):  
Genetic Variation ◽  
Environmental Conditions ◽  
Phage Type ◽  
Resistance Breeding ◽  
Wide Range ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Main Components ◽  
Host Parasite ◽  
Relationship Of

SummaryVariations in the host–parasite relationship of bacterial blight of cotton, caused by Xanthomonas malvacearum, E. F. Smith (Dowson), axe elucidated in terms of the three main components of variation, namely, genetic variation in the host, genetic variation in the parasite and variations in environment.Although the relative resistance shown by host varieties differed both with the culture of the pathogen used for inoculation and with the environmental conditions, over-riding patterns of host resistance could be detected, showing that certain varieties maintained their resistance over a wide range of conditions.It was found that phage type in X. malvacearum was not related to virulence. Moreover, none of the cultures of the pathogen which had been isolated from different sources, could be shown to be identical when inoculated into a range of host varieties under a range of environmental conditions. It was concluded that the pathogen showed continuous variation in virulence and that it would be difficult and of little value to attempt to define races.Some success was achieved in relating observed variations in the host–parasite relationship to easily measured components of the environment, by using multiple regression analyses. It is suggested that this might provide a means of characterizing the complex variations observed and that the host–parasite relationship could be regarded as a dynamic system, in which disease expression is a function of the interactions of environmental factors and two polygenic systems, that of the host and that of the parasite.Intrapopulation variances were also studied in the host varieties. A population which showed little variation for resistance under one set of conditions might show considerable variation in a different environment or when inoculated with a different culture. It is suggested that selection for resistance under conditions which favour the expression of variation can lead, by repeated selection and inbreeding, to the production of resistant populations which retain their resistance under conditions in which the parental stocks showed no worthwhile resistance. These conclusions are discussed in relation to problems in resistance breeding and genetics.

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