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.
There is evidence that the introgression is a ubiquitous phenomenon in plants, even in animals and perhaps it also exists among pre-human lineages (Holliday 2003).
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.
- 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
introgression in German: Introgression
introgression in Italian: Introgression line
introgression in Japanese: 遺伝子汚染