Introgression

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Introgression, in genetics (particularly plant genetics), is the movement of a gene (gene flow) from one species into the gene pool of another by backcrossing an interspecific hybrid with one of its parents. Introgression is a long-term process; it may take many hybrid generations before the backcrossing occurs. An example of introgression is that of a transgene from a transgenic plant to a wild relative as the result of a successful hybridization leading to intentional or unintentional "genetic pollution". Another important example has been studied by Arnold & Bennett 1993: irises species from southern Louisiana.^[1]

There is evidence that the introgression is a ubiquitous phenomenon in plants, even in animals^[2]^[3] and perhaps it also exists among pre-human lineages (Holliday 2003^[4]).

An introgression line (abbreviation: IL) in plant molecular biology is a line of a crop species that contains genetic material derived from a similar species, for example a "wild" relative. An example of a collection of ILs (called IL-Library) is the use of chromosome fragments from Solanum pennellii (a wild variety of tomato) introgressed in Solanum lycopersicum (the cultivated tomato). The lines of an IL-Library covers usually the complete genome of the donor. Introgression lines allow the study of quantitative trait loci, but also the creation of new varieties by introducing exotic traits.

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[edit] References

^ Arnold, M. L. & Bennett, B. D. (1993). "Natural Hybridization in Louisiana irises: genetic variation and ecological determinants". In: Harrison, R. G. (ed.) Hybrid Zones and Evolutionary Process, pp. 115-139. Oxford University Press, New York. ISBN 978-0195069174
^ Dowling, T. E. & Secor, C. L. (1997). The role of hybridization and introgression in the diversification of animals. Annual Review Ecology and Systematics 28:593-619.
^ Bullini, L. 1994. Origin and evolution of animal hybrid species. Trends in Ecology and Evolution 9: 422–426.
^ Holliday, T. W. (2003). Species concepts, reticulations, and human evolution. Current Anthropology 44: 653–673.

Anderson, E. 1949. Introgressive Hybridization. Wiley, New York.
Eyal Friedman et al., "Zooming In on a Quantitative Trait for Tomato Yield Using Interspecific Introgressions", Science vol.305 pag.1786-1798 (2004)
Rieseberg, L. H. & Wendel, J. F. (1993). "Introgression and its consequences in plants". In: Harrison, R. G. (ed.) Hybrid Zones and Evolutionary Process, pp. 70-109. Oxford University Press, New York. ISBN 978-0195069174