What are near-isogenic lines (NILs)?
A set of lines that are genetically identical, except for one or a few loci. Such lines can be created by crossing a donor line (containing a gene or trait of interest) with a recurrent parent to produce a heterozygous F1, and then repeatedly back-crossing the offspring to the recurrent parent (BC1, BC2, etc), retaining the donor gene or trait in each successive generation. Marker assisted selection (MAS) can be used to increase the efficiency of NIL development by screening individuals for the presence of the target locus (gene) in each generation and the absence of extraneous donor DNA throughout the rest of the genome to speed up the return to recurrent parent type.
