Gene-for-gene relationships in plant parasitic systems

The specificity of host : parasite interactions is under the control of their respective genetic systems. H. H. Flor designed experiments to unfold the genetic basis of these interactions using flax as the host and flax rust as the parasite. He concluded that for each resistance gene (R-gene) in the...

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Bibliographic Details
Published in:Science progress (1916) 1975-01, Vol.62 (247), p.467-485
Main Author: Sidhu, G.S
Format: Article
Language:English
Subjects:
Disease resistance
flax
fungi
Genotypes
Host parasite relationships
Medical genetics
Melampsora lini
Parasite hosts
Parasites
Parasitic diseases
Parasitism
Population genetics
rust diseases
Virulence
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Summary:The specificity of host : parasite interactions is under the control of their respective genetic systems. H. H. Flor designed experiments to unfold the genetic basis of these interactions using flax as the host and flax rust as the parasite. He concluded that for each resistance gene (R-gene) in the host there is a specific and related virulence gene (V-gene) in the parasite. This type of numerical equivalence between the R-genes and the V-genes led Flor to formulate his hypothesis of a gene-for-gene relationship. Theoretical evaluation of this hypothesis eventually led C. O. Person to conclude that such relationships should occur as a general rule in host : parasite systems. These relationships have been shown to operate in more than twenty-five parasitic systems. They show that the R-genes and the V-genes are usually inherited as dominant and recessive characteristics respectively. Nevertheless the overall simplified pattern (quadratic check) which they generate as a result of specific interaction, is independent of dominant and recessive relationships of the R-genes and the V-genes. Gene-for-gene interactions aid in understanding the nature of relationships between the hosts and their parasites, both from the evolutionary and practical point of view. It seems too early to assign any definitive role to genetic polymorphism for the maintenance of a dynamic equilibrium between the hosts and parasites under natural and man-guided systems. However, the gene-for-gene hypothesis can lead to a much better understanding of these phenomena which should facilitate the long-term control of economically important diseases.
ISSN:0036-8504
2047-7163