Backbred

Backbred is a term used in genetics and plant, animal, or horticultural breeding to describe individuals or lines produced by backcrossing a hybrid to one of its parents or to a genetically close relative. Such backbred lines aim to recover most of the recurrent parent’s genome while retaining a desired trait from the donor.

Backcrossing begins with crossing a donor line carrying the trait of interest with a recurrent parent with preferred characteristics to create a hybrid (the F1). The F1 is then crossed back to the recurrent parent, producing BC1 offspring. This process is repeated (BC2, BC3, etc.). With each generation, the proportion of the recurrent parent genome increases while the donor genome is diluted, although donor alleles linked to the target trait can be retained if selected for. Modern programs often use marker-assisted selection to identify individuals with the desired locus and a high proportion of recurrent background.

Backbred materials are used to introgress specific characteristics—such as disease resistance, pest tolerance, quality traits, or environmental adaptation—into elite cultivars or lines. In livestock and horticulture, backbreeding serves to combine favorable production traits with newly introduced characteristics while preserving the overall performance of the recurrent line.

Limitations include linkage drag, where undesirable donor traits accompany the target allele; the need for several generations and significant screening; and the possibility that the donor trait may not be perfectly recovered in all environments. Backbred lines are typically tested across environments to confirm stability and performance.

Backbred contrasts with simple crossbreeding, which mixes genomes without repeated backcrossing to a recurrent line, and with backcrossing alone, which focuses on transferring a trait while retaining the recurrent background.