What is inbreeding? Explain the phenomenon of decreased viability of offspring with inbreeding. What is the purpose of inbreeding in breeding? Describe the genetic qualities of inbred lines
Inbreeding, or inbreeding (from the English, in – inside and breeding – breeding), is the crossbreeding in breeding of individuals with a close degree of kinship (brother – sister, father – daughter, mother – son). Inbreeding is carried out to transfer genes into a homozygous state and to stabilize the characteristics of a variety or breed. In self-pollinating plants (wheat, barley, peas, etc.), inbreeding is a common occurrence. In cross-pollinated plants and animals, prolonged inbreeding can lead to reduced viability, anomalies, malformations, and even death of some offspring. The reason for this phenomenon is the transition of recessive lethal genes, as well as genes that reduce viability, to a homozygous state with phenotypic manifestation in closely related homozygotes of harmful recessive mutations. For example, with self-pollination of corn in the progeny of one mother plant, gradual is observed. decreased growth intensity, fertility, the occurrence of various deformities.
Since inbred individuals become homozygous for normal genes, including those that determine economically valuable traits, they steadily transmit them to offspring. The offspring resulting from inbreeding is called the inbred line. It is homozygous for most genes and does not split characters in generations. Inbred lines are used later in breeding work for breeding in order to obtain heterozygotes that differ from homozygous parental forms in their greater viability and productivity.