Genetic Polymorphism in Parasitic Systems

Person, Clayton

doi:10.1038/212266a0

Cited by 71 publications

(34 citation statements)

References 6 publications

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“…A stable pathogen population solves the host's problem of maintenance of resistance to a disease, while the pathogen is able to survive without eliminating its host (MODE, 1958) . PERSON (1966) came to similar conclusion .…”

Section: Polygenic Resistance and Pathogenicity ; A Modelsupporting

confidence: 69%

The integrated concept of disease resistance: A new view including horizontal and vertical resistance in plants

1977

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SUMMARYHorizontal, uniform, race-non-specific or stable resistance can be discerned according to Van der Plank, from vertical, differential, race-specific or unstable resistance by a test in which a number of host genotypes (cultivars or clones) are tested against a number of pathogen genotypes (races or isolates) . If the total non-environmental variance in levels of resistance is due to main effects only (differences between cultivars and differences between isolates) the resistance and the pathogenicity (in the broad sense) are horizontal in nature . Vertical resistance and pathogenicity are characterized by the interaction between host and pathogen showing up as a variance component in this test due to interaction between cultivars and isolates .A host and pathogen model was made in which resistance and pathogenicity are governed by five polygenic loci . Within the host the resistance genes show additivity . Two models were investigated ; in model I resistance and pathogenicity genes operate in an additive way as envisaged by Van der Plank in his horizontal resistance . Model II is characterized by a gene-for-gene action between the polygenes of the host and those of the pathogen .The cultivar/isolate test in model I showed only main effect variance . Surprisingly, the variance in model II was also largely due to main effects . The contribution of the interaction to the variance appeared so small, that it would be difficult to discern it from a normal error variance .So-called horizontal resistance can therefore be explained by a polygenic resistance, where the individual genes are vertical and operating on a gene-for-gene basis with virulence genes in the pathogen . The data reported so far support the idea that model II rather than model I is the realistic one .The two models also revealed that populations with a polygenic resistance based on the gene-forgene action have an increased level of resistance compared with the addition model, while its stability, as far as mutability of the pathogen is concerned, is higher compared to those with an additive gene action . Mathematical studies of Mode too support the gene-for-gene concept .The operation of all resistance and virulence genes in a natural population is therefore seen as one integrated system . All genes for true resistance in the host population, whether they are major or minor genes, are considered to interact in a gene-for-gene way with virulence genes, either major or minor, in the pathogen population .The models revealed other important aspects . Populations with a polygenic resistance based on a gene-for-gene action have an increased level of resistance compared to populations following the addition model . The stability, as far as mutability of the pathogen is concerned, is higher in the interaction model than in the addition model .The effect of a resistance gene on the level of resistance of the population consists of its effect 5 on a single plant times its gene frequency in the population . Due to the adaptive forces in both the host and...

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Section: Polygenic Resistance and Pathogenicity ; A Modelsupporting

confidence: 69%

The integrated concept of disease resistance: A new view including horizontal and vertical resistance in plants

1977

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“…The evolutionary processes responsible for the polymorphism of this trait at the LD site remain unclear. Most theoretical discussions of host-pathogen coevolution have argued that natural selection should almost inevitably lead to polymorphism (Haldane, 1949;Person, 1966;Clarke, 1976;Levin eta!., 1982;Tooby, 1982). However, it is questionable whether the LD polymorphism is maintained by any type of balancing selection.…”

Section: Discussionmentioning

confidence: 99%

Constraints on the evolution of disease resistance in an annual legume

Parker

1993

Heredity

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“…According to this hypothesis, for each resistance gene in the host there is a specific and related gene for virulence in those pathogens to which it is susceptible. This relationship has been detected by several investigators in many host-parasite systems (Person, 1966). But how do gene-for-gene relationships arise and how are they maintained in biological systems ?…”

Section: Gene-for-gene Theorymentioning

confidence: 97%

“…Where the pressure is specific and the population under pressure adjusts itself, the response is also specific (Person et al, 1962). When it is supposed that the genetic base of the parasitic system is polymorphic, and there is some evidence for this (Person, 1966), under certain conditions, the host-parasite system eventually reaches a state of stable equilibrium.…”

Section: Gene-for-gene Theorymentioning

confidence: 99%

Host-pathogen interaction as a special case of interrelations between organisms

Linskens

1968

Netherlands Journal of Plant Pathology

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Plants are open systems and therefore maintain a vast number of complex relationships with the environment. Among these are: 1. Dependencies upon the external environment. 2. Strong influences on the environment. 3. Diverse interrelations with other organisms at different levels, of plant species among each other, and of plants with animals including human beings. According to the nature of the interaction various types of interrelations can be distinguished: (a) neutral relations (e.g. epiphytes), (b) mutualistic relations (fertilization, symbiosis), and (c) parasitic relations (incompatibility, the phytopathological host-parasite interactions). Pathogens can be defined as organisms out of place. As a result of special conditions defense reactions are observed in the stricken individuals such as irregular reactions on the metabolic level, formation of phytoalexins, competition for food, space, etc., involving also genetic interrelationships between hosts and their parasites. Such interrelations occurring on the cellular level include the problems of cell recognition, adherence of the cell surfaces to each other, and intercellular bridging. Interactions on the individual population and ecosystem levels can be reduced to aspects of the interactions, which involve mutual gene regulation.The position ofphytopathology within the biological sciences can be in a way described as an association between botany and biochemistry, an association which includes close relations with ecology, zoology, agricultural technology, and biophysics. Moreover, phytopathology deals with a general problem of biology, namely, the interaction of living cells. Organisms as open systems

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Genetic Polymorphism in Parasitic Systems

Cited by 71 publications

References 6 publications

The integrated concept of disease resistance: A new view including horizontal and vertical resistance in plants

The integrated concept of disease resistance: A new view including horizontal and vertical resistance in plants

Constraints on the evolution of disease resistance in an annual legume

Host-pathogen interaction as a special case of interrelations between organisms

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