Inbred strain

As an inbred line is referred to known which emerged from close inbreeding nearly homozygous progeny of a plant or an animal, in their genetic ancestry (gene pool ) are described, their outer ( phenotypic ) Appearance and Features in detail and their homozygous propagation is possible, so that the described features are maintained in subsequent generations.

Plant breeding

In plant breeding, inbred lines are used and the basis of many successful Saatzuchtprogramme. In artificial selfing of individual plants it comes in the offspring to an accumulation of (mostly) negative and (more rarely) positive gene combinations. The proportion of the loaded ( depressive ) Descendants is approximately seventy percent of open-pollinated plants. Only about ten percent of the progeny there is a positive combination of genes - these plants are selfed again.

After about seven inbred generations in maize breeding the offspring considered as homozygous inbred line and these are applied for protection of property rights at the Federal Office for Plant Variety Protection. In order to optimize the time-consuming process, both growing seasons of earth can be used. After the autumn harvest in the northern hemisphere, the seed is to sow spent on the southern hemisphere to be returned in the spring for another breeding step. From an economic perspective is a prerequisite for the creation of inbred lines the short reproduction time and the low value of the individual or of the individual plant.

By crossing two inbred lines arise F1 hybrids. The greater the genetic distance between the two homozygous breeding lines, the higher is the probability of a high heterosis ( reached by crossing efficiency ) of the hybrids. The best heterosis effects are achieved when the crossed inbred lines from very distant genetic resources originate.

Animal husbandry

Inbred lines of animals are artificially generated genetically homogeneous populations, which are necessary among other things for the standardization of scientific experiments on animals. Particularly common are inbred lines in use (more than two hundred such lines are known).

In order to obtain a stable inbred line must be grown for at least twenty generations in a consistent brother-sister mating. During the breeding phase there is inbreeding depression, which can be overcome by purging. This is done through a strict selection of breeding animals: more than 70 % of the offspring are taken out of it because they are not sufficiently vital. The twentieth generation is 99.4 % homozygous ( homozygous ) and sufficiently stable usually in the form of the desired features.

The crossing two inbred lines are called hybrid breeding. It serves the utilization of heterosis effect which is greater, the greater the genetic distance between inbred lines used. This method is for example used for breeding of laying hens