Introducing a gene from a donor parent to enhance a cultivar for a certain attribute is one of the objectives of plant breeding. One possible application for wild germplasm is as a source of resistance to disease. The breeder also wants to avoid introducing any more wild germplasm genes that could lower the cultivar's agronomic fitness. One way to introduce a particular gene into plants is through the backcross method of plant breeding. Linkage drag is one genetic characteristic of backcross breeding, though. This is the decrease in a cultivar's fitness brought about by the introduction of harmful genes during backcrossing with favorable ones. With the use of molecular markers, one can keep track of how much DNA from the wild or alien species is present in each backcross generation. Sterility loci that create barriers during breeding and prevent the formation of recombinant progenies with desired characteristics may be the cause of linkage drag. There are loci associated with hybrid sterility loci that are linked to resistance, yield, and other desirable features. For a plant breeder, it is favorable when two or more loci controlling distinct desired traits are linked. Two distinct desirable qualities can be improved simultaneously if there is a relationship between their genes. However, undesirable traits have not been able to flow from cultivars to wild relatives due to reproductive barriers such hybrid sterility and linkage drag. The linkage drag can be illuminated again through back crossing advanced molecular techniques. With the advancement of molecular marker technology, linkage drag would be easier to eliminate.

Keywords: Linkage drag, back cross, undesirable gene, Molecular markers