Introgression

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. [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 ]

There is evidence that the introgression is a ubiquitous phenomenon in plants, even in animals [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.] and perhaps it also exists among pre-humanlineages (Holliday 2003 [Holliday, T. W. (2003). Species concepts, reticulations, and human evolution. "Current Anthropology" 44: 653–673.] ).

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.

ee also

*Gene flow
*Transgene
*Hybridization
*Genetic engineering
*Genetically modified organism
*Transgenic plant
*Chimera (genetics)
*Gene pool
*Genetic pollution
*Genetic erosion

References

* 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